SecProbe.io

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 March 6, 2026

Erica McLaughlin
Executive Vice President and Chief Financial Officer
CABOT CORP
Two Seaport Lane
Suite 1400
Boston, MA 02210

 Re: CABOT CORP
 Form 10-K filed November 24, 2025
 File No. 001-05667
Dear Erica McLaughlin:

 We have completed our review of your filing. We remind you that the
company and its
management are responsible for the accuracy and adequacy of their disclosures,
notwithstanding
any review, comments, action or absence of action by the staff.

 Sincerely,

 Division of
Corporation Finance
 Office of Industrial
Applications and Services
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 March 3, 2026   Division of Corporation Finance Office of Industrial Applications and Services United States Securities and Exchange Commission Washington, D.C. 20549   Re: Cabot Corporation Form 10-K filed November 24, 2025 File No. 001-05667   Dear Ms. Baker and Mr. O’Brien:   This letter is being submitted in response to the Staff’s comment letter on February 19, 2026 regarding Cabot Corporation’s Annual Report on Form 10-K for the fiscal year ended September 30, 2025. For ease of reference, we have restated the Staff’s comment before our response below.   Form 10-K for the Year Ended September 30, 2025 Management’s Discussion and Analysis Results of Operations Definition of Terms and Non-GAAP Financial Measures, page 30   As noted on page 31, your non-GAAP measure, total segment EBIT, excludes unallocated corporate overhead expenses, such as certain corporate salaries and headquarters expenses, plus costs related to special projects and initiatives. As such, this non-GAAP measure appears to exclude normal, recurring, cash operating expenses and may therefore not comply with Rule 100(b) of Regulation G and Item 10(e) of Regulation S-K. With specific reference to Question 100.01 of the Division of Corporation Finance’s Compliance & Disclosure Interpretations on Non-GAAP Financial Measures, please confirm you will revise future filings, including earnings releases filed under Form 8-K, to eliminate this measure.   Cabot Response: We understand the Staff’s comment and acknowledge the guidance in Question 100.01 of the Division of Corporation Finance’s Compliance & Disclosure Interpretations on Non-GAAP Financial Measures. In future filings, as well as our earnings releases furnished on Current Reports on Form 8-K, we will eliminate the disclosure of total segment EBIT.

 If you have any questions regarding the Company’s response, please do not hesitate to contact Lisa Dumont, Cabot’s Chief Accounting Officer, at 617-342-6020 and Jane Bell, Cabot’s Corporate Secretary and Chief Counsel – Securities and Governance, at 617-342-6035.   Kind Regards, / s / Erica McLaughlin _______________________ Erica McLaughlin Executive Vice President and Chief Financial Officer   Cc: Sean Keohane Karen Kalita Jane Bell Lisa Dumont Erika Ordway (Deloitte & Touche LLP)

February 19, 2026
Erica McLaughlin
Executive Vice President and Chief Financial Officer
CABOT CORP
Two Seaport Lane
Suite 1400
Boston, MA 02210
Re:CABOT CORP
Form 10-K filed November 24, 2025
File No. 001-05667
Dear Erica McLaughlin:
            We have reviewed your filing and have the following comment.
            Please respond to this letter within ten business days by providing the requested
information or advise us as soon as possible when you will respond. If you do not believe the
comment applies to your facts and circumstances, please tell us why in your response.
            After reviewing your response to this letter, we may have additional comments.
Form 10-K for the Year Ended September 30, 2025
Managment's Discussion and Analysis
Results of Operations
Definition of Terms and Non-GAAP Financial Measures, page 30
1.As noted on page 31, your non-GAAP measure, total segment EBIT, excludes
unallocated corporate overhead expenses, such as certain corporate salaries and
headquarters expenses, plus costs related to special projects and initiatives. As such, this
non-GAAP measure appears to exclude normal, recurring, cash operating expenses and
may therefore not comply with Rule 100(b) of Regulation G and Item 10(e) of
Regulation S-K. With specific reference to Question 100.01 of the Division of
Corporation Finance’s Compliance & Disclosure Interpretations on Non-
GAAP Financial Measures, please confirm you will revise future filings, including
earnings releases filed under Form 8-K, to eliminate this measure.

            We remind you that the company and its management are responsible for the accuracy
and adequacy of their disclosures, notwithstanding any review, comments, action or absence of

February 19, 2026
Page 2
action by the staff.
            Please contact Jeanne Baker at 202-551-3691 or Terence O'Brien at 202-551-3355 if you
have questions regarding comments on the financial statements and related matters.
Sincerely,
Division of Corporation Finance
Office of Industrial Applications and
Services

United States securities and exchange commission logo
May 3, 2022
Erica McLaughlin
Senior Vice President and Chief Financial Officer
CABOT CORP
Two Seaport Lane
Suite 1400
Boston, Massachusetts 02210
Re:CABOT CORP
Form 10-K for the Fiscal Year Ended September 30, 2021
Filed November 29, 2021
File No. 001-05667
Dear Ms. McLaughlin:
            We have completed our review of your filing.  We remind you that the company and its
management are responsible for the accuracy and adequacy of their disclosures, notwithstanding
any review, comments, action or absence of action by the staff.
Sincerely,
Division of Corporation Finance
Office of Life Sciences

CORRESP
1
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CORRESP

 Cabot Corporation

Two Seaport Lane

 Suite 1400

Boston, MA 02210-2019

 United
States

 April 14, 2022

 VIA
EDGAR

 U.S. Securities and Exchange Commission

Division of Corporation Finance

 Office of Life Sciences

100 F Street, N.E.

 Washington, D.C. 20549

Attention:
 Margaret Schwartz / Laura Crotty – Legal

Jeanne Bennett / Brian Cascio – Accounting

Re:
 Cabot Corp.

Form 10-K for the Fiscal Year Ended September 30, 2021

Response Letter dated March 18, 2022

File No. 001-05667

Ladies and Gentlemen:

 This letter is being
submitted in response to the comment letter dated April 4, 2022 from the staff of the Division of Corporation Finance (the “Staff”) of the Securities and Exchange Commission relating to the above-referenced Response Letter of Cabot
Corp. (the “Company” or “Cabot”). For reference purposes, we have restated the comment contained in the Staff’s letter dated April 4, 2022 before our response below.

Response dated March 18, 2022

 Item 1A. Risk
Factors, page 14

 We note your response to our prior comments number 2 and 4. We do not see disclosure regarding the risks involving enforcement of
laws or the risk that rules and regulations can change quickly with little notice. Please revise your risk factors section to specifically state, with respect to China and other jurisdictions as appropriate, the risks arising from the legal
system(s), including risks and uncertainties regarding the enforcement of laws, and that rules and regulations can change quickly with little advance notice. Your disclosure should make clear and specifically state whether these risks could result
in a material change in your operations and/or the value of your securities.

 Response to Comment 1:

We acknowledge the Staff’s comment and propose enhancing our disclosure in our risk factor addressing political or country risk in future
filings by modifying the description of the risk, substantially as follows:

 T +1 617 345 0100 | F
+1 617 342 6103 | cabotcorp.com

Securities and Exchange Commission

 -
 2
 -

April 14, 2022

 “We are exposed to political or country risk inherent in doing business in some
countries, including China.

 Sales outside of the U.S. constituted the majority of our revenues in fiscal 2021. We conduct business in
several countries, including China, that have less stable legal systems and financial markets, and potentially more corrupt, or less predictable, business environments than the U.S. As set forth in Note U to our Consolidated Financial Statements,
sales in China constituted approximately 25% of our revenues in fiscal 2021 and our property, plant and equipment located in China constituted approximately 25% of our total property, plant and equipment as of September 30, 2021. Our
operations outside of the U.S., including in China, expose us to risks related to uncertain enforcement of laws by foreign governments as well as risks that foreign governmental entities will change applicable rules and regulations with minimal
advance notice. These risks could result in a material change in our operations, which could negatively impact the value of our securities. Additionally, o Our operations in some countries, including China, are
subject to the following risks: changes in the rate of economic growth; unsettled political or economic conditions; non-renewal of operating permits or licenses; possible expropriation or other governmental
actions; corruption by government officials and other third parties; social unrest, war, terrorist activities or other armed conflict; confiscatory taxation or other adverse tax policies; deprivation of contract rights; trade regulations affecting
production, pricing and marketing of products; reduced protection of intellectual property rights; restrictions or additional costs associated with repatriating cash; exchange controls; inflation; currency fluctuations and devaluation; political
tension that could result in sanctions being imposed against our customers or suppliers in countries where sanctions have not been imposed in the past; the effect of global health, safety and environmental matters on economic conditions and market
opportunities; and changes in financial policy and availability of credit.

 For example, tThe Chinese government
has, from time to time, curtailed manufacturing operations, with little or no notice, in industrial regions out of growing concern over air quality. The timing and length of these curtailments are difficult to predict and, at times, are applied to
manufacturing operations without regard to whether the operations being curtailed comply with environmental regulations in the area. Accordingly, our manufacturing operations in China have been subject to these curtailments in the past and will
likely be subject to them in the future. In addition, the Chinese government has instituted energy intensity and energy consumption targets in a number of provinces in its efforts to reduce energy consumption, resulting in energy quotas and
shortages in energy supply. We are unable to predict how any power outages related to these targets will impact our operations. These events could negatively impact our results of operations and cash flows both during and after the period of any
government-imposed curtailment or power outages affecting our operations. Further, any such curtailments on the operations at our customers’ facilities could reduce demand for our products and our volumes.”

*        *         *

 T +1 617 345 0100
| F +1 617 342 6103 | cabotcorp.com

Securities and Exchange Commission

 -
 3
 -

April 14, 2022

 We would be happy to discuss our response with you at your convenience. Please do not
hesitate to call Jane Bell, the Company’s Corporate Secretary and Chief Counsel – Securities and Governance, at (617) 342-6035 with any questions.

Very truly yours,

 /s/ Erica McLaughlin

 Erica McLaughlin

 Senior Vice President and
Chief Financial Officer

cc:
 Sean Keohane

Karen Kalita

 Jane Bell

Paul Kinsella (Ropes & Gray LLP)

William Michener (Ropes & Gray LLP)

 T +1 617 345 0100
| F +1 617 342 6103 | cabotcorp.com

United States securities and exchange commission logo
April 4, 2022
Erica McLaughlin
Senior Vice President and Chief Financial Officer
CABOT CORP
Two Seaport Lane
Suite 1400
Boston, Massachusetts 02210
Re:CABOT CORP
Form 10-K for the Fiscal Year Ended September 30, 2021
Response Letter dated March 18, 2022
File No. 001-05667
Dear Ms. McLaughlin:
            We have reviewed your March 18, 2022 response to our comment letter and have the
following comment.  In our comment we may ask you to provide us with information so we may
better understand your disclosure.
            Please respond to this comment within ten business days by providing the requested
information or advise us as soon as possible when you will respond.  If you do not believe our
comment applies to your facts and circumstances, please tell us why in your response.
            After reviewing your response to this comment, we may have additional
comments.  Unless we note otherwise, our references to prior comments are to comments in our
March 4, 2022 letter.
Response dated March 18, 2022
Item 1A. Risk Factors, page 14
1.We note your response to our prior comments number 2 and 4. We do not see disclosure
regarding the risks involving enforcement of laws or the risk that rules and regulations can
change quickly with little notice. Please revise your risk factors section to specifically
state, with respect to China and other jurisdictions as appropriate, the risks arising from
the legal system(s), including risks and uncertainties regarding the enforcement of laws,
and that rules and regulations can change quickly with little advance notice. Your
disclosure should make clear and specifically state whether these risks could result in a
material change in your operations and/or the value of your securities.

 FirstName LastNameErica McLaughlin
 Comapany NameCABOT CORP
 April 4, 2022 Page 2
 FirstName LastName
Erica McLaughlin
CABOT CORP
April 4, 2022
Page 2
            You may contact Jeanne Bennett at 202-551-3606 or Brian Cascio at 202-551-3676 if
you have questions regarding comments on the financial statements and related matters.  Please
contact Margaret Schwartz at 202-551-7153 or Laura Crotty at 202-551-7614 with any other
questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences

CORRESP
1
filename1.htm

CORRESP

 Cabot Corporation

Two Seaport Lane

 Suite 1400

Boston, MA 02210-2019

 United
States

 March 18, 2022

 VIA
EDGAR

 U.S. Securities and Exchange Commission

Division of Corporation Finance

 Office of Life Sciences

100 F Street, N.E.

 Washington, D.C. 20549

Attention:
 Margaret Schwartz / Laura Crotty – Legal

 Jeanne Bennett / Julie Sherman – Accounting

Re:
 Cabot Corp.

 Form 10-K for the Fiscal Year Ended September 30, 2021

 Filed November 29, 2021

 File No. 001-05667

Ladies and Gentlemen:

 This letter is being
submitted in response to the comment letter dated March 4, 2022 from the staff of the Division of Corporation Finance (the “Staff”) of the Securities and Exchange Commission relating to the above-referenced Annual Report on Form 10-K
of Cabot Corp. (the “Company” or “Cabot”). For reference purposes, we have restated the comments contained in the Staff’s letter dated March 4, 2022 before our responses below.

Form 10-K for the Fiscal Year Ended September 30, 2021

Item 1. Business, page 4

 At the outset of Part
1, please provide prominent disclosure about the legal and operational risks associated with the company having substantial operations in China. Your disclosure should make clear whether these risks could result in a material change in your
operations and/or the value of your securities or could significantly limit or completely hinder your ability to offer or continue to offer securities to investors and cause the value of such securities to significantly decline or be worthless. Your
disclosure should address how recent statements and regulatory actions by China’s government, such as those related to data security or anti-monopoly concerns, have or may impact the company’s ability to conduct its business and/or accept
foreign investments.

 Response to Comment 1:

We acknowledge the Staff’s comment, and propose adding, in future filings, the disclosure set forth below in Part 1, under the heading
“General”, following the description of our segment operations.

 T +1 617 345 0100
| F +1 617 342 6103 | cabotcorp.com

Securities and Exchange Commission

 -
 2
 -

March 18, 2022

 “Each of our segments operates globally, and a significant portion of our revenues and
operating profits is derived from operations outside the U.S. In particular, China continues to be an important producer of tires and products for automotive applications and since we made our initial investment in China in 1988, we have increased
our operations in China to support increased demand for our products in China. In addition, a significant portion of battery manufacturers are located in China, and we anticipate a material portion of the future growth of our Battery Materials
growth vector to be derived from our business and operations in China. We employ local management teams for our operations in China, and our business model in China is predominantly to make and sell product in-country to established local and
multi-national customers with operations in China. In fiscal 2021, sales in China across our segments constituted approximately 25% of our revenues, and our property, plant and equipment located in China constituted approximately 25% of our total
property, plant and equipment as of September 30, 2021. (See Note U to our Consolidated Financial Statements). There are legal and operational risks associated with having substantial operations in China, which are more fully described under
the heading “Risk Factors”, including the risks described under the headings: “We are exposed to political or country risk inherent in doing business in some countries, including China”; “Information technology systems
failures, data security breaches, cybersecurity attacks or network disruptions could compromise our information, disrupt our operations and expose us to liability, which may adversely impact our operations”; “The continued protection of
patents, trade secrets and other proprietary intellectual property rights are important to our success”; “Negative or uncertain worldwide or regional economic conditions or trade relations may adversely impact our business” and
“Our tax rate is dependent upon a number of factors, a change in any of which could impact our future tax rates and net income”. Given the size of our current operations in China and the future growth we anticipate from those operations,
if our ability to operate in China were to be constrained by legal and operational risks, it could have a material negative impact on our overall operations and the value of our securities.”

Given the nature of Cabot’s business-to-business operations and how Cabot’s data is classified under the Cyberspace Administration
of China (the “CAC”), as well as our relative market positions within China, the Company does not believe that recent statements and regulatory actions by China’s government, such as those related to data security or anti-monopoly
concerns, meaningfully impact the Company’s ability to conduct its business or issue its securities. Accordingly, at this time, we are not proposing disclosure for our future filings that would address this question. We undertake to monitor
changes that warrant supplemental disclosure.

 Disclose each permission or approval that you or your subsidiaries are required to obtain from Chinese
authorities to operate your business and to offer securities to foreign investors. State whether you or your subsidiaries are covered by permissions requirements from the China Securities Regulatory Commission (CSRC), Cyberspace Administration of
China (CAC) or any other governmental agency, and state affirmatively whether you have received all requisite permissions or approvals and whether any permissions or approvals have been denied. Please also describe the consequences to you and your
investors if you or your subsidiaries: (i) do not receive or maintain such permissions or approvals, (ii) inadvertently conclude that such permissions or approvals are not required, or (iii) applicable laws, regulations, or
interpretations change and you are required to obtain such permissions or approvals in the future.

 T +1 617 345 0100
| F +1 617 342 6103 | cabotcorp.com

Securities and Exchange Commission

 -
 3
 -

March 18, 2022

 Response to Comment 2:

We obtain certain general business and environmental licenses in the ordinary course of business. To date, we have received all such material
permissions and approvals required to operate our business in China. Outside of these general business and environmental licenses obtained in the ordinary course of business, our subsidiaries and joint venture operations in China are not required to
obtain permissions or approval from Chinese authorities to operate our business in China, including permissions or approvals from the China Securities Regulatory Commission (“CSRC”), the CAC, or any other governmental agency under laws
currently in effect. Specifically, as a corporation organized under the laws of the State of Delaware, Cabot is not required to obtain any permissions from the CSRC or other Chinese regulatory agencies to issue securities. With respect to the
requirements from the CAC, given the nature of Cabot’s business-to-business operations and how Cabot’s data is classified under the CAC’s rules, we do not anticipate being required to obtain any permissions or approvals from the CAC
or that compliance with CAC requirements will have a material impact on our operations. We undertake to monitor changes in this area that may warrant disclosure. The Personal Information Protection Law of the People’s Republic of China (PIPL)
does apply to Cabot and its handling of personal information. We are in the process of developing and implementing policies and procedures to comply with the requirements of the PIPL that are applicable to Cabot, but given the nature of Cabot’s
business and the size of our employee population in China, we do not believe Cabot is required to obtain permissions from Chinese regulatory authorities under the PIPL to conduct its business or that compliance with these requirements will have a
material impact on our operations.

 To address this comment, in future filings, in our discussion of risks associated with information
technology in our risk factors, we expect to include a specific reference to the PIPL. By way of example, we have set forth below this proposed disclosure.

“The global regulatory environment pertaining to information security and privacy is increasingly demanding, with new and changing requirements, such as
the European Union’s General Data Protection Regulation (“GDPR”), the China Cybersecurity Law, The Personal Information Protection Law of the People’s Republic of China (“PIPL”), and
Brazil’s Lei Geral de Protecao de Dados (“LGDP”). Complying with these laws and regulations may be more costly or take longer than we anticipate, and could otherwise affect our business operations any failure to
comply may result in fines or penalties.”

 Please revise your disclosure to provide a clear description of how cash is transferred through
your organization, addressing the following:

 Disclose your intentions to distribute earnings.

Quantify any cash flows and transfers of other assets by type that have occurred between the holding company and its Chinese subsidiaries,
and the direction of transfer.

 Quantify any dividends or distributions that a Chinese subsidiary has made to the holding company
and which entity made such transfer, and their tax consequences. Similarly, please quantify dividends or distributions made to U.S. investors, the source, and their tax consequences. Your disclosure should make clear if no transfers, dividends, or
distributions have been made to date.

 T +1 617 345 0100
| F +1 617 342 6103 | cabotcorp.com

Securities and Exchange Commission

 -
 4
 -

March 18, 2022

 Describe any restrictions on foreign exchange and your ability to transfer cash between
entities, across borders, and to U.S. investors.

 Describe any restrictions and limitations on your ability to distribute earnings
from the company, including your Chinese subsidiaries to the parent company and U.S. investors.

 Response to Comment 3:

We have cash pooling structures that support our operations in the U.S., EMEA and China and allow for the flow of cash between our
subsidiaries. We use local cash generation to support the local operating needs, to fund capital expenditures and acquisitions and to pay minority interest payments to shareholders. We also deploy cash through a global pool to support the
needs of other subsidiaries and regions. We face limited restrictions on the flow of cash. Argentina has currency controls in place that prevent the distribution of cash, but otherwise we are generally able to move funds around the globe
through our cash pools, intercompany accounts and/or distributions, as needed. We also are able to repatriate cash to the U.S., if needed, including cash from China, while paying any withholding or other taxes; however, we consider most cash we
generate in geographies outside the U.S. indefinitely reinvested outside the U.S.

 With respect to the Staff’s comment about cash
flows involving our entities in China, our operations in China are self-sustaining, and, therefore, investment from abroad is not required. Cabot has an onshore cash pool that is connected via intercompany accounts to our global
pool. Excess cash in China can be deployed through the global pool to support other non-U.S. subsidiaries and operations and/or investments outside of China. As a result of the flexibility and fluidity of the cash pooling structures, we do
not regularly distribute earnings out of China, but we do not have restrictions in making distributions to the U.S. of our after-tax profits, less required allocations to a statutory reserve fund, should we choose to do so. Our holding company in
China has made the required allocations. Distributions from China to the U.S. generally would be subject to a 10% withholding tax.

 Within
China, dividends paid by our operating subsidiaries and distributions made to us by our joint venture operations are to our holding company in China and generally remain in China to support our operational activities and investments in China. Over
the last ten years, we have repatriated cash to the U.S. from our holding company in China in one fiscal year. This repatriation was in fiscal year 2019 in the aggregate amount of $150 million and was subject to tax withholding of $15 million.
From time to time, we may repatriate additional funds from China in the future; however, we consider most cash we generate in China indefinitely reinvested in China. Further, over the last ten years, we have not transferred cash from the U.S. to our
operations in China. There are currently no legal restrictions or limitations on the ability of our Chinese operating subsidiaries or joint venture operations to pay dividends or otherwise distribute after-tax earnings (less any required allocations
to a statutory reserve fund), including to entities outside China.

 In future filings, to address this comment, we propose enhancing our
disclosures in “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources—Overview” by modifying our discussion of our cash needs substantially as follows:

 T +1 617 345 0100
| F +1 617 342 6103 | cabotcorp.com

Securities and Exchange Commission

 -
 5
 -

March 18, 2022

 “A significant portion of our business occurs outside the U.S and our cash generation
does not always align geographically with our cash needs. The vast majority of our cash and cash equivalent holdings tend to be held outside the U.S. We generally use a combination of U.S. earnings, commercial paper issuances and borrowings under
our U.S. Credit Agreement to meet our U.S. cash needs, and cash held by foreign subsidiaries is generally used to finance the subsidiaries’ operational activities and future investments. We are currently using a combination of
commercial paper and borrowings from the U.S. Credit Agreement to meet our U.S. cash needs. We generally reduce our commercial paper balance and, if applicable, borrowings under our Credit Agreements, at quarter-end using cash derived from
customer collections, settlement of intercompany balances and short-term intercompany loans. We also have cash pooling structures that support our operations in the U.S., EMEA and China and provide access to cash for our non-U.S. subsidiaries
through the global pool. We face limited restrictions on the flow of cash. Argentina has currency controls in place that prevent the distribution of cash, but otherwise we are able to move funds between our non-U.S. subsidiaries through
our cash pools, intercompany accounts and/or distributions, as needed. If additional funds are needed in the U.S., we expect to be able to repatriate funds or to access additional debt under the Credit Agreements. As of
September 30, 2021, we had $71 million of commercial paper outstanding and our borrowings under the Euro Credit Agreement totaled $134 millioncash, including cash from China, while paying any withholding or other taxes. However, we
consider most cash we generate in geographies outside the U.S. indefinitely reinvested. Changes in tax laws in the U.S. or foreign countries could restrict our ability to transfer funds or impose material costs of such transfers.”

Item 1A. Risk Factors, page 14

 Please revise
your risk factors section to specifically discuss risks arising from the legal system in China, including risks and uncertainties regarding the enforcement of laws and that rules and regulations in China can change quickly with little advance
notice. In this regarding we note the disclosure you have included on page 20, but ask that you provide more detailed disclosure regarding the regulatory risks associated with your oper

United States securities and exchange commission logo
March 4, 2022
Erica McLaughlin
Senior Vice President and Chief Financial Officer
CABOT CORP
Two Seaport Lane
Suite 1400
Boston, Massachusetts 02210
Re:CABOT CORP
Form 10-K for the Fiscal Year Ended September 30, 2021
Filed November 29, 2021
File No. 001-05667
Dear Ms. McLaughlin:
            We have limited our review of your filing to the financial statements and related
disclosures and have the following comments.  In some of our comments, we may ask you to
provide us with information so we may better understand your disclosure.
            Please respond to these comments within ten business days by providing the requested
information or advise us as soon as possible when you will respond.  If you do not believe our
comments apply to your facts and circumstances, please tell us why in your response.
            After reviewing your response to these comments, we may have additional comments.
Form 10-K for the Fiscal Year Ended September 30, 2021
Item 1. Business, page 4
1.At the outset of Part 1, please provide prominent disclosure about the legal and
operational risks associated with the company having substantial operations in China.
Your disclosure should make clear whether these risks could result in a material change in
your operations and/or the value of your securities or could significantly limit or
completely hinder your ability to offer or continue to offer securities to investors and
cause the value of such securities to significantly decline or be worthless. Your disclosure
should address how recent statements and regulatory actions by China’s government, such
as those related to data security or anti-monopoly concerns, have or may impact the
company’s ability to conduct its business and/or accept foreign investments.
2.Disclose each permission or approval that you or your subsidiaries are required to obtain

 FirstName LastNameErica McLaughlin
 Comapany NameCABOT CORP
 March 4, 2022 Page 2
 FirstName LastNameErica McLaughlin
CABOT CORP
March 4, 2022
Page 2
from Chinese authorities to operate your business and to offer securities to foreign
investors. State whether you or your subsidiaries are covered by permissions requirements
from the China Securities Regulatory Commission (CSRC), Cyberspace Administration of
China (CAC) or any other governmental agency, and state affirmatively whether you have
received all requisite permissions or approvals and whether any permissions or approvals
have been denied. Please also describe the consequences to you and your investors if you
or your subsidiaries: (i) do not receive or maintain such permissions or approvals, (ii)
inadvertently conclude that such permissions or approvals are not required, or (iii)
applicable laws, regulations, or interpretations change and you are required to obtain such
permissions or approvals in the future.
3.Please revise your disclosure to provide a clear description of how cash is transferred
through your organization, addressing the following:
•Disclose your intentions to distribute earnings.
•Quantify any cash flows and transfers of other assets by type that have occurred
between the holding company and its Chinese subsidiaries, and the direction of
transfer.
•Quantify any dividends or distributions that a Chinese subsidiary has made to the
holding company and which entity made such transfer, and their tax consequences.
Similarly, please quantify dividends or distributions made to U.S. investors, the
source, and their tax consequences. Your disclosure should make clear if no transfers,
dividends, or distributions have been made to date.
•Describe any restrictions on foreign exchange and your ability to transfer cash
between entities, across borders, and to U.S. investors.
•Describe any restrictions and limitations on your ability to distribute earnings from
the company, including your Chinese subsidiaries to the parent company and U.S.
investors.
Item 1A. Risk Factors, page 14
4.Please revise your risk factors section to specifically discuss risks arising from the legal
system in China, including risks and uncertainties regarding the enforcement of laws and
that rules and regulations in China can change quickly with little advance notice. In this
regarding we note the disclosure you have included on page 20, but ask that you provide
more detailed disclosure regarding the regulatory risks associated with your operations
and revenue from China.
5.In light of recent events indicating greater oversight by the Cyberspace Administration of
China (CAC) over data security, please revise your disclosure to explain if and how this
oversight impacts your business and to what extent you believe that you are compliant
with the regulations or policies that have been issued by the CAC to date, if applicable.
            In closing, we remind you that the company and its management are responsible for the
accuracy and adequacy of their disclosures, notwithstanding any review, comments, action or
absence of action by the staff.

 FirstName LastNameErica McLaughlin
 Comapany NameCABOT CORP
 March 4, 2022 Page 3
 FirstName LastName
Erica McLaughlin
CABOT CORP
March 4, 2022
Page 3
            You may contact Jeanne Bennett at (202) 551-3606 or Julie Sherman at (202) 551-3640 if
you have questions regarding comments on the financial statements and related matters. Please
contact Margaret Schwartz at (202) 551-7153 or Laura Crotty at (202) 551-7614 with any other
questions
Sincerely,
Division of Corporation Finance
Office of Life Sciences

Mail Stop 4631

July 26 , 2016

Via E -mail
Mr. Eduardo E. Cordeiro
Executive Vice President and Chief Financial Officer
Cabot Corporation
Two Seaport Lane
Boston, MA  02210 -2019

RE: Cabot Corporation
Form 10 -K for the Year Ended September 30, 2015
Filed November 25, 2015
  File No. 1 -5667

Dear Mr. Cordeiro:

We have completed our review of your filing .  We remind you that our comments or
changes to disclosure in response to our comments do not foreclose the Commission from taking
any action with respect to the company or the filing and the company may not assert staff
comments as a defense in any proceeding initiated by the Commission or any person under the
federal securities la ws of the United States.  We urge all persons who are responsible for the
accuracy and adequacy of the disclosure in the filing to be certain that the filing include s the
information the Securities Exchange Act of 1934 and all applicable rules require.

Sincerely,

/s/ John Cash

John Cash
Accounting Branch Chief
Office of Manufacturing and
Construction

CORRESP
1
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CORRESP

 July 8, 2016

John Cash, Accounting Branch Chief

 Division of Corporation
Finance

 United States Securities and Exchange Commission

Washington, D.C. 20549

Re:
Cabot Corporation

 File No. 1-5667

Dear Mr. Cash:

 This letter is being submitted in response
to the Staff’s comment letter of June 23, 2016 in respect of Cabot Corporation’s Form 10-K for the fiscal year ended September 30, 2015 and Item 2.02 Form 8-K filed May 2, 2016. For ease of reference, we have restated
the Staff’s comments before our responses below.

 Form 10-K for the Year Ended September 30, 2015

Item 6. Selected Financial Data, page 20

1.
We have the following comments regarding the presentation of your non-GAAP measures Adjusted Return on Invested Capital and Adjusted Return on Net Assets:

•

In accordance with Item 10(e)(1)(A) and (B) of Regulation S-K, please present, with equal or greater prominence, the most directly comparable financial measures calculated and presented in accordance
with Generally Accepted Accounting Principles (GAAP) and a reconciliation of the differences between the non-GAAP financial measure with the most directly comparable GAAP financial measure;

Cabot Response:

 We acknowledge the Staff’s
comment and in future filings, when we present Adjusted Return on Net Assets or Adjusted Return on Invested Capital, we will include, with equal prominence, the most directly comparable financial measure calculated using amounts determined in
accordance with Generally Accepted Accounting Principles (GAAP) and present a quantitative reconciliation with the most directly comparable GAAP financial measure. The following represents an example of the quantitative reconciliation of Adjusted
Return on Net Assets, which will reflect all periods presented:

20XX

 Return on Net Assets

 Income (loss) from continuing
operations(a)

$
 X

 Net assets(b)

$
 X

 Return on net assets

X
%

 Adjusted Return on Net Assets

 Adjusted net income (loss)(a):

 Income (loss) from continuing operations

$
 X

 Less: Certain items, net of tax benefit(c)
$X

X

   Adjusted net income (loss)

$
 X

 Adjusted net assets(d):

 Adjusted net working capital(e)

$
 X

 Net property, plant and equipment

X

 Assets held for rent

X

 Equity affiliates

X

 Adjusted net assets

$
 X

 Adjusted return on net assets

X
%

(a)
Income (loss) from continuing operations and Adjusted net income (loss) are aggregated four quarter rolling amounts.

(b)
Net assets represents Total stockholders’ equity.

(c)
Tax impact on certain items is discussed in note XX.

(d)
Each component of adjusted net assets is calculated by averaging previous five quarter ending balances.

(e)
Adjusted net working capital is the average previous five quarter ending balances of Accounts receivable plus Inventory less Accounts payable and accruals.

•

As presented in Notes (4) and (5), we note these non-GAAP measures include the after-tax impact of the items identified without a clear explanation for how the tax effect is calculated. These
presentations may be inconsistent with the updated Compliance and Disclosure Interpretations issued on May 17, 2016. Please review this guidance when preparing your future filings; and

Cabot Response:

 We acknowledge the Staff’s
comment and in future filings, we will present the income tax effect on the items identified and explain how the tax effect was derived.

•

Management believes these non-GAAP financial measures are useful to investors as a measure of performance and the effectiveness of your use of capital. Please revise your disclosure in future filings to
provide adequately detailed information specific to your circumstances as to why these non-GAAP measures are useful to investors. Refer to Item 10(e)(1)(i)(C) of Regulation S-K.

Cabot Response:

 We acknowledge the Staff’s
comment with respect to adjusted Return on Net Assets (“RONA”) and adjusted Return on Invested Capital (“ROIC”), as well as with respect to other non-GAAP measures we have included in our filings, and when we provide non-GAAP
measures in future filings we will provide adequately detailed information specific to our circumstances as to why these measures are useful to investors. In this regard, we direct the Staff’s attention to our response to Comment 6, where we
have provided a preliminary draft of the disclosure we expect to provide in future filings explaining why we believe adjusted EPS is a useful measure to our investors. We would expect to include a similar level of disclosure in our description of
why each of our non-GAAP measures is useful to our investors.

 With respect to adjusted RONA, we calculate this measure by dividing adjusted net income
(loss) by adjusted net assets. In the numerator of the calculation, we exclude certain items of income and expense that management does not consider representative of our ongoing results. We direct the Staff’s attention to our response to
Comment 6 where we have provided a preliminary draft of the disclosure we expect to provide in future filings explaining why we exclude these certain items from these non-GAAP measures of financial performance and why management believes these
non-GAAP measures are useful to investors.

 With respect to our calculation of adjusted net assets, in this calculation we only include our operational
assets (principally Net property, plant and equipment and Working capital) that are under management’s control in the management of the business and are the drivers of our operating results. In addition, we calculate Net assets on a rolling
five quarters average to normalize the impact of large inter-period movements, such as our management of working capital or volatility in feedstock prices. Adjusted RONA is also a key metric used to measure performance under our management incentive
compensation programs, and accordingly, we believe it is useful to our investors.

 Item 7. Management’s Discussion and Analysis of
Financial Condition and Results of Operations, page 24

 Definition of Terms and Non-GAAP Financial Measures, page 29

2.
You indicate that Total Segment EBIT is a non-GAAP financial measure that provides useful supplemental information for your investors as it is an important indicator of your operational strength and performance.
Please revise your disclosure in future filings to provide adequately detailed information specific to your circumstances as to why this non-GAAP measure is useful to investors. Refer to Item 10(e)(1)(i)(C) of Regulation S-K.

 Cabot Response:

 We
acknowledge the Staff’s comment. If and when we present Total Segment EBIT as a non-GAAP financial measure in future filings, we will revise our disclosure to provide adequately detailed information specific to our Company’s circumstances
as to why this non-GAAP measure is useful to investors in accordance with Item 10(e)(1)(i)(C) of Regulation S-K.

 Provision for Income Taxes and
Reconciliation of Effective Tax Rate to Operating Tax Rate, page 32

3.
We note that you have provided a reconciliation of your effective tax rate to your operating tax rate, a non-GAAP financial measure. Please identify the nature of the unusual or infrequent items, items related to
uncertain tax positions and other discrete items in each period. We also note that this presentation may be inconsistent with the updated Compliance and Disclosure Interpretations issued on May 17, 2016. Please review this guidance when
preparing your future filings.

 Cabot Response:

In future filings, we will disclose the nature of the unusual or infrequent items, items related to uncertain tax positions and other discrete items included
in our reconciliation of the effective tax rate to the operating tax rate. The nature of these items in the reconciliation included in our Form 10-K for the year ended September 30, 2015 was as follows:

(i)
Unusual or infrequent items included tax benefits from items such as extraordinary dividends from subsidiaries, the renewal of U.S. Research and Experimental credit, and the release of valuation allowance and interest
on uncertain tax positions.

(ii)
Items related to uncertain tax positions included tax benefits from items such as uncertain tax positions accrual reversals due to the expiration of statutes of limitations and settlement of tax audits, offset by a
charge for the accrual of interest on uncertain tax positions.

(iii)
Other discrete tax items included tax charges for items such as charges for various return to provisions true ups related to tax return filings, changes in tax laws or status, changes in judgment on the realizability of
certain deferred tax assets and/or unremitted foreign earnings.

 Form 8-K Filed May 2, 2016

4.
Please address the above comments on your earnings release as well, as applicable.

 Cabot
Response:

 In our response to the Staff’s comment number 6, we have provided, by way of illustration, draft disclosure of the type we expect
to include in future filings to provide adequately detailed information specific to our circumstances as to why our non-GAAP measures are useful to investors. In future earnings releases, if and when we present Total Segment EBIT, we will revise our
disclosure to provide adequately detailed information specific to our Company’s circumstances as to why this non-GAAP measure is useful to investors in accordance with Item 10(e)(1)(i)(C) of Regulation S-K. Additionally, in future earnings
releases, we will disclose the nature of the unusual or infrequent items, items related to uncertain tax positions and other discrete items included in our reconciliation of the effective tax rate to the operating tax rate.

5.
We remind you that Item 10(e)(1)(i)(a) of Regulation S-K indicates that you should not present non-GAAP financial measures with greater prominence than the most directly comparable GAAP financial measures. The
following presentations appear inconsistent with the updated Compliance and Disclosure Interpretations issued on May 17, 2016. Please review this guidance when preparing your next earnings release:

•

You present non-GAAP adjusted EPS before your GAAP diluted EPS in your earnings release headline;

Cabot Response:

 We acknowledge the Staff’s
comment and in future earnings releases we will present our GAAP diluted EPS before our non-GAAP adjusted EPS.

•

Your narrative appears to place more prominence on non-GAAP financial measures such as adjusted EBITDA and adjusted EPS without providing a discussion of the corresponding GAAP financial measures;

 Cabot Response:

 We
acknowledge the Staff’s comment and in future earnings releases, we will revise our narrative to ensure that equal or greater prominence is placed on the corresponding GAAP financial measures.

•

You do not provide a quantitative reconciliation with respect to your forward-looking non-GAAP measures.

Cabot Response:

 We acknowledge the Staff’s
comment and in future earnings releases and other filings, we will provide a quantitative reconciliation between any forward-looking non-GAAP measures presented and the most directly comparable GAAP measure. The associated reconciling items are
currently expected to consist of information that is known and available without unreasonable efforts. In the event that a reconciliation requires “unreasonable efforts” as stated in item 10(e)(1)(i)(B), we will disclose that fact and
describe the nature of information that is unavailable.

 Explanation of Terms and Use of Non-GAAP Measures

6.
You believe that the non-GAAP financial measures adjusted EPS, Total Segment EBIT, operating tax rate and adjusted EBITDA assist your investors in evaluating the changes in your results and the Company’s
performance. We also note that you believe that Total Segment EBIT provides useful supplemental information for your investors as it is an important indicator of the Company’s operations strength and performance. Please revise your disclosure
in future filings to provide adequately detailed information specific to your circumstances as to why each of these non-GAAP measures are useful to investors. Refer to Item 10(e)(1)(i)(C) of Regulation S-K.

Cabot Response:

 We have set forth below a
preliminary draft of the disclosure we expect to include in future filings to provide adequately detailed information specific to our circumstances as to why adjusted EPS is a useful measure for investors. We would expect to include a similar level
of disclosure in our description of why the other non-GAAP measures we provide are useful to investors in evaluating the changes in our results and performance.

“Use of non-GAAP financial measures.

 To supplement
Cabot’s consolidated financial statements presented on a generally accepted accounting principles (“GAAP”) basis, Cabot provides non-GAAP measures, which include Adjusted EPS, Adjusted EBITDA, Adjusted ROIC, and Adjusted RONA. These
non-GAAP financial measures are not computed in accordance with, or as an alternative to, generally accepted accounting principles in the United States. Reconciliations of each of these non-GAAP financial measures to GAAP information are also
included.

 Management believes these non-GAAP measures provide investors with greater transparency to the information used by Cabot management in its
financial and operational decision-making, allow investors to see Cabot’s results through the eyes of management, and better enable Cabot’s investors to understand Cabot’s operating performance and financial condition.

In calculating Adjusted EPS, we exclude from our net income (loss) per share from continuing operations items of expense and income that management does not
consider representative of the Company’s on-going business operations. Accordingly, reporting earnings on an adjusted basis supplements the GAAP measure of performance and provides additional information related to the underlying performance of
the business. For example, certain of the items we exclude are items that we are required by GAAP to recognize in one period that relate to activities extending over several periods or relate to single events that management considers to be unusual
and infrequent and not reflective of ongoing operations. We refer to these items as “certain items”. Management believes excluding these items facilitates operating performance comparisons from period to period by eliminating differences
caused by the existence and timing of certain expense and income items that would not otherwise be apparent on a GAAP basis. Management also uses adjusted EPS as a key measure in evaluating management performance for incentive compensation
purposes.”

 In future filings, the discussion of our non-GAAP measures will provide adequately detailed information specific to our circumstances as
to why identified costs or income items are considered certain items. By way of example, we have set forth below detailed information providing our reasons for excluding selected certain items from Adjusted EPS as reported in our earnings release
included as an exhibit to the May 2, 2016 Form 8-K.

 “Specifically, in calculating Adjusted EPS we have excluded the impact of the following items:

•

Global restructuring activities include costs or benefits associated with cost reduction initiatives or plant closures and are primarily related to (i) employee termination costs, (ii) asset impairment
charges, (iii) costs to close facilities, including environmental costs and contract termination penalties and (iv) gains realized on the sale of land or equipment. We exclude these costs or benefits because they do not reflect our
underlying business operations, they may relate to other periods and not only the period in which they are recognized, and management evaluates the Company’s operating performance without the impact of these costs or benefits.

•

Foreign currency loss on devaluation represents the impact of controlled currency devaluations on the Company’s net mo

Mail Stop 4631

June 23, 2016

Via E -mail
Mr. Eduardo E. Cordeiro
Executive Vice President and Chief Financial Officer
Cabot Corporation
Two Seaport Lane
Boston, MA  02210 -2019

RE: Cabot Corporation
Form 10 -K for the Year Ended September 30, 2015
Filed November 25 , 2015
Item 2.02 Form 8 -K
Filed May 2, 2016
File No. 1 -5667

Dear Mr. Cordeiro :

We have limited our review  of your filing  to the financial statements and related
disclosures and have the following comments.  In some of our comments, we may ask you to
provide us with information so we may better understand your disclosure.

Please respond to these comments  within ten busine ss days by providing the requested
informa tion or advis e us as soon as possible when you will respond.  If you do not believe our
comments apply to your facts and circumstances, please  tell us why in your response.

After reviewing your response to these  comments, we may have  additional comments.

Form 10 -K for the Year Ended September 30, 2015

Item 6. Selected Financial Data, page 20

1. We have the following comments regarding the presentation of your non -GAAP
measures Adjusted Return on Invested Capital and Adjusted Return on Net Assets:
 In accordance with Item 10(e)(1)(A) and (B) of Regulation S -K, please present,
with equal or greater prominence, the most directly comparable financial
measures calculated and presented in accordance with Generally Accepted
Accounting Princi ples (GAAP) and a reconciliation of the differences between the
non-GAAP financial measure with the most directly comparable GAAP financial
measure;

Mr. Eduardo E. Cordeiro
Cabot Corporation
June 23 , 2016
Page 2

  As presented in Notes (4) and (5), we note these non -GAAP measures include the
after-tax impact of the ite ms identified without a clear explanation for how the tax
effect is calculated.  These presentations may be inconsistent with the updated
Compliance and Disclosure Interpretations  issued on May 17, 2016.  Please
review this guidance when preparing your fut ure filings; and
 Management believes these non -GAAP financial measures are useful to investors
as a measure of performance and the effectiveness of your use of capital.  Please
revise your disclosure in future filings to provide adequately detailed information
specific to your circumstances as to why these non -GAAP measures are useful to
investors.   Refer to Item 10( e)(1)(i)(C) of Regulation S -K.

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of
Operations, page 2 4

Definition of Terms and Non -GAAP Financial Measures, page 29

2. You indicate that Total Segment EBIT is a non -GAAP financial measure that provides
useful supplemental information for your investors as it is an important indicator of your
operational stren gth and performance.  Please revise your disclosure in future filings to
provide adequately detailed information specific to your circumstances as to why this
non-GAAP measure is useful to investors.  Refer to Item 10(e)(1)(i)(C) of Regulation S -
K.

Provis ion for Income Taxes and Reconciliation of Effective Tax Rate to Operating Tax Rate,
page 32

3. We note that you have provided a reconciliation of your effective tax rate to your
operating tax rate, a non -GAAP financial measure.  Please identify the nature o f the
unusual or infrequent items, items related to uncertain tax positions and other discrete
items in each period.  We also note that t his presentation may be inconsistent with the
updated Compliance and Disclosure Interpretations  issued on May 17, 2016.   Please
review this guidance when preparing your future filings.

Form 8 -K Filed May 2, 2016

4. Please address the above comments on your earnings release as well, as applicable.

5. We remind you that Item 10(e)(1)(i)(a) of Regulation S -K indicates that you should not
present non -GAAP financial measures with greater prominence than the most directly
comparable GAAP financial measures.  The following  presentations appear inconsistent
with the updated Compliance and Disclosure Interpretations  issued on May 17, 2016.
Please review this guidance when preparing your next earnings release :
 You present non -GAAP adjusted EPS before your GAAP diluted EPS in your
earnings release headline;

Mr. Eduardo E. Cordeiro
Cabot Corporation
June 23 , 2016
Page 3

  Your narrative appears to place more prominence on non -GAAP financial
measures s uch as adjusted EBITDA and adjusted EPS without providing a
discussion of the corresponding GAAP financial measures; and
 You do not provide a quantitative reconciliation with respect to your forwar d-
looking non -GAAP measures.

Explanation of Terms and  Use of Non -GAAP Measures

6. You believe that the non -GAAP financial measures adjusted EPS, Total Segment EBIT,
operating tax rate and adjusted EBITDA assist your investors in evaluating the changes in
your results and the Company’s performance.  We also not e that you believe that Total
Segment EBIT provides useful supplemental information for your investors as it is an
important indicator of the Company’s operations strength and performance.  Please revise
your disclosure in future filings to provide adequat ely detailed information specific to
your circumstances as to why each of these non -GAAP measures are useful to investors.
Refer to Item 10( e)(1)( i)(C) of Regulation S -K.

Adjusted EBITDA

7. Under the caption, Explanation of Terms Used and Use of Non -GAAP  measures, you
indicate that “Adjusted EBITDA” is a non -GAAP financial measure and refers to
earnings before interest, taxes, depreciation and amortization, excluding items that
management does not consider representative of the fundamental segment results .  We
have the following comments in this regard:
 You indicate that a reconciliation of adjusted EBITDA from segment EBIT for
the second quarter of fiscal year 2016 is provided on the investor portion of your
website.  Please revise future filings to inclu de a reconciliation to your most
directly comparable GAAP measure and ensure this reconciliation is included in
your filing; and
 Under the caption, Cash Performance, you state that you generated adjusted
EBITDA of $117 million during the second quarter of fiscal 2016.  Based on the
inclusion of this information in your discussion of cash performance, it appears
that you also use this measure as a liquidity measure.  If so, please provide all the
disclosures required by Item 10(e(1)(i)(A),(B) and (C) in futu re filings.

Table 1: Detail of Certain Items
Table 4: Reconciliation of Operating Tax Rate
Table 5: Reconciliation of Adjusted EPS by Quarter Fiscal 2016 and Fiscal 2015

8. We note that your presentations of certain items include the tax impact of these it ems
witho ut a clear explanation for how the tax effect is calculated.  These presentations may
be inconsistent with the updated Compliance and Disclosure Interpretations  issued on
May 17,  2016.  Please review this guidance when preparing your next earnings  release .

Mr. Eduardo E. Cordeiro
Cabot Corporation
June 23 , 2016
Page 4

 9. Please explain the nature of the discrete tax -related certain items.

We urge all persons who are responsible for the accuracy and adequacy of the disclosure
in the filing to be certain that the filing includes the information the Securities Exchange Act of
1934 and all applica ble Exchange Act rules require.   Since the company and its management are
in possession of all facts relating to a company’s disclosure, they are responsible for the accuracy
and adequacy of t he disclosures they have made.

In responding to our comments, please provide  a written statement from the company
acknowledging that:

 the company is responsible for the adequacy and accuracy of the disclosure in the
filing;

 staff comments or changes to disclosure in response to staff comments do not
foreclose the Commission from taking any action with respect to the filing; and

 the company may not assert staff comments as a defense in any proceeding initiated
by the Commission or any person under the  federal securities laws of the United
States.

You may contact Jeffrey Gordon, Staff Accountant, at (202) 551 -3866 or Jeanne Baker,
Assistant Chief Accountant, at (202) 551 -3691  with any questions.

 Sincerely,

 /s/ John Cash

 John Cash
 Accounting Branch Chief
Office of Manufacturing and
Construction

May 4, 2015

Via E -mail
Eduardo E. Cordeiro
Chief Financial Officer
Cabot Corporation
Two Seaport Lane
Boston, MA  02210 -2019

Re: Cabot Corporation
 Form 10-K for the Fiscal Year Ended September 30, 2014
Filed November 26, 2014
File No. 1 -5667

Dear Mr. Cordeiro :

We have completed our review of your filing s.  We remind you that our comments or
changes to disclosure in response to our comments do not foreclose the Commission from taking
any action with respect to the company or the filing s and the company may not assert staff
comments as a defense in any proceeding initiated by the Commission or any person under the
federal securities laws of the United States.  We urge all persons who are responsible for the
accuracy and adequacy of the disclosure in the filing s to be certain that the filing s include the
information the Securities Exchange Act of 1934 and all applicable rules require.

Sincerely,

/s/ John Cash

John Cash
Accounting Branch Chief

CORRESP
1
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Correspondence

 April 27, 2015

John Cash, Accounting Branch Chief

 Division of Corporation
Finance

 United States Securities and Exchange Commission

Washington, D.C. 20549

Re:

Cabot Corporation

File No. 1-5667

 Dear Mr. Cash:

 This
letter is being submitted in response to the Staff’s comment letter of April 15, 2015 in respect of Cabot Corporation’s Form 10-K for the fiscal year ended September 30, 2014. For ease of reference, we have restated the
Staff’s comments before our responses below.

 Item 1. Business, page 3

Operations, page 9

1.
Please tell us if you have considered additional mining property disclosure pursuant to the Instructions to Item 102 of Regulation S-K. We generally consider additional Industry Guide 7 mining property
disclosure to be necessary if the total asset value of the aggregate of all mining properties exceeds 10% of total assets. We consider mining properties to include properties used from the point of mineral extraction to the first point of sales. In
your response, please tell us how you measure the materiality or significance of your mining properties. Based on your response, we may have additional comments.

Cabot Response:

 As disclosed in our Form 10-K for
the fiscal year ended September 30, 2014, we own a pollucite mine in Manitoba and a lignite mine in Texas, which is operated by Caddo Creek Resources Company, LLC. Operations at the mine in Texas began subsequent to September 30,
2014. Our mining operations at these mines are limited to obtaining raw materials to produce certain of our products; pollucite is the principal raw material used in our Specialty Fluids business, and lignite is the principal raw material we
use to manufacture activated carbon for certain applications sourced from our Marshall, Texas facility. We have considered the property disclosure requirements contained in Item 1.02 of Regulation S-K and its Instructions and believe we
have included the information material to an understanding of the Company’s business as a whole, and in particular regarding the availability of raw materials for certain of our products in light of our ownership of these mines. With
respect to Instruction 7 of Item 1.02 and our analysis of whether additional property disclosure under Industry Guide 7 may be necessary, the total asset value of the aggregate of all of our mining properties, from the point of mineral
extraction to the first point of sale, as of September 30, 2014, was less than 5% of Cabot’s total consolidated assets. Accordingly, we concluded that Cabot is not engaged in significant mining operations and that the property
description called for in Industry Guide 7 is not required.

 Management’s Discussion and Analysis, page 30

2.
 Please revise this section in future filings to include, if material, substantive disclosure on prospective developments and strategies that may
affect your company. Your current disclosure on page 36 contains a list of factors that broadly affect your segments, but there is no disclosure addressing management’s views about the trends and uncertainties that you reasonably expect will
have a material impact on your operations. We note that in an earnings call on October 29, 2014, management expressed expectations for a number of items including oil prices, global macroeconomic conditions, raw materials, currency fluctuations
and end market demand for each of your segments. In the future, to the extent material, please

enhance your discussion of any particular trends, events or uncertainties that you expect may have a material impact on your operations. Please see Section III.B.3 of SEC Release 33-8350 and
Item 303(a)(3)(ii) of Regulation S-K.

 Cabot Response:

We acknowledge the Staff’s comment and in future filings, we will include in our Management’s Discussion and Analysis, to the extent material, a
discussion of any known trends or uncertainties that we expect may have a material impact on our operations.

 As requested, in connection with responding
to the Staff’s comments, the Company hereby acknowledges that (i) the Company is responsible for the adequacy and accuracy of the disclosure in its filings, (ii) Staff comments or changes to disclosure in response to Staff comments do
not foreclose the Commission from taking any action with respect to the filing, and (iii) the Company may not assert Staff comments as a defense in any proceeding initiated by the Commission or any person under the federal securities laws of
the United States.

 We would be happy to discuss any of our responses with you at your convenience. Please do not hesitate to call Jim Kelly, Cabot’s
Controller, at 617-342-6020 and Jane Bell, Cabot’s Corporate Secretary and Chief Counsel – Securities and Governance, at 617-342-6035 with any questions.

Very truly yours,

 /s/ Eduardo E. Cordeiro

Eduardo E. Cordeiro

Executive Vice President and Chief Financial Officer

Cc:

Patrick M. Prevost

Brian A. Berube

James P. Kelly

Jane A. Bell

Brian McAllister (Deloitte & Touche LLP)

April 15, 2015

Via E -mail
Eduardo E. Cordeiro
Chief Financial Officer
Cabot Corporation
Two Seaport Lane
Boston, MA  02210 -2019

Re: Cabot Corporation
 Form 10-K for the Fiscal Year Ended September 30, 2014
Filed November 26, 2014
File No. 1 -5667

Dear Mr. Cordeiro :

We have reviewed your filing an d have the following comments.  In some of our
comments, we may ask you to provide us with information so we may better understand  your
disclosure.

Please respond to these comments  within ten busine ss days by providing the requested
information or advis e us as soon as possible when you will respond.  If you  do not believe our
comments apply to your facts and circumstances , please  tell us why in your response.

After reviewing your response to these  comments, we may have  additional comments.

Item 1. Business , page 3

Operations, page 9

1. Please tell us if you have considered additional mining property disclosu re pursuant to
the Instructions to Item 102 of Regulation S -K.  We generally consider additional
Industry Guide 7 mining property disclosure to be necessary if the total asset value of the
aggregate of all mining properties exceeds 10% of total assets.  We consider mining
properties to include properties used from the point of mineral extraction to the first point
of sales.   In your response, please tell us how you measure the materiality or significance
of your mining properties.  Based on your response , we may have additional comment s.

Eduardo E. Cordeiro
Cabot Corporation
April 15, 2015
Page 2

 Management’s Discussion and Analysis …, page 30

2. Please revise this section in future filings to include, if material, substantive disclosure
on prospective developments and strategie s that may affect your company.   Your c urrent
disclosure on page 36 contains a list of factors that broadly affect your segments, but
there is no disclosure addressing management’s views about the trends and uncertainties
that you reasonably expect will have a material impact on your operations .  We note that
in an earnings call on October 29, 2014, management expressed expectations for a
number of items including oil prices, global macroeconomic conditions, raw materials,
currency fluctuations and end market de mand for each of your segments.   In the future,
to the extent material, please enhance your discussion of any particular trends, events or
uncertainties that you expect may have a material impact on your operations.  Please see
Section III.B.3 of SEC Release 33 -8350 and Item 303(a)(3)(ii) of Regulation S -K.

We urge all persons who are responsible for the accuracy and adequacy of the disclosure
in the filing to be certain that the filing includes the information the Securities Exchange Act of
1934 and all applicable Exchange Act rules req uire.  Since the company and its management are
in possession of all facts relating to a company’s disclosure, they are responsible for the accuracy
and adequacy of t he disclosures they have made.

In responding to our comments, please provide  a written statement from the company
acknowledging that:

 the company is responsible for the adequacy and accuracy of the disclosure in the
filing;

 staff comments or changes to disclosure in response to staff comments do not
foreclose the Commission from  taking any action with respect to the filing; and

 the company may not assert staff comments as a defense in any proceeding initiated
by the Commission or any person under the federal securities laws of the United
States.

You may contact Lisa Etheredge, Staff Accountant, at (202) 551 -3424  or Jeanne Baker,
Staff Accountant,  at (202) 551 -3691  if you have questions regarding comments on the financial
statements and re lated matters.  Please contact Leland Benton, Staff Attorney , at (202) 551 -3791
or Pamela Long, Assistant Director,  at (202) 551 -3765 with any other questions.

Sincerely,

 /s/ John Cash

John Cash
Accounting Branch Chief

March 20, 2014

Via E -mail
Eduardo E. Cordeiro
Chief Financial Officer
Cabot Corporation
Two Seaport Lane
Boston, MA  02210 -2019

Re: Cabot Corporation
 Form 10-K for the Fiscal Year Ended September 30, 2013
Filed November 27, 2013
File No. 1 -5667

Dear Mr. Cordeiro :

We have completed our review of your filings .  We remind you that our comments or
changes to disclosure in response to our comments do not foreclose the Commission from taking
any action with respect to the company or the filing s and the company may not assert staff
comments as a defense in any proceeding initiated by the Commission or any person under the
federal securities laws of the United States.  We urge all pe rsons who are responsible for the
accuracy and adequacy of the disclosure in the filing s to be certain that the filing s include  the
information the Securities Exchange Act of 1934 and all applicable rules require.

Sincerely,

/s/ John Cash

John Cash
Accounting Branch  Chief

CORRESP
1
filename1.htm

Correspondence

 March 18, 2014

John Cash, Accounting Branch Chief

 Division of Corporation
Finance

 United States Securities and Exchange Commission

Washington, D.C. 20549

Re:
Cabot Corporation

File No. 1-5667

 Dear Mr. Cash:

This letter is being submitted in response to the Staff’s comment letter of March 7, 2014 in respect of Cabot Corporation’s Form 10-K for the
fiscal year ended September 30, 2013 and Form 10-Q for the quarter ended December 31, 2013. For ease of reference, we have restated the Staff’s comments before our responses below.

Form 10-K for the Year Ended September 30, 2013

Management’s Discussion and Analysis…, page 32

Goodwill and Long-Lived Assets, page 34

1.
You disclose on page 34 that your Purification Solutions business had goodwill of $466 million as of September 30, 2013 and that the growth of this reporting unit is highly dependent on the growth in the mercury
removal portion of this business. Please tell us if the estimated fair value of your Purification Solutions reporting unit substantially exceed the carrying value of this reporting unit as of your most recent goodwill impairment test.

 Cabot Response:

 The
Purification Solutions reporting unit was created with the acquisition of Norit on July 31, 2012. Because this reporting unit consists solely of the acquired business, its carrying value equaled its fair value as of the acquisition date. During
our annual goodwill impairment test performed as of May 31, 2013, we determined that the fair value of the Purification Solutions reporting unit exceeded its carrying value by approximately 20%, which we determined to be substantial. This
determination was based upon facts and circumstances, including the excess of fair value over carrying value, taking into account the level of uncertainty associated with the methods and assumptions used in the impairment testing. Notably, those
assumptions included the expected growth in earnings from the mercury removal portion of the Purification Solutions business, which represent management’s best estimates and we believe are reasonable. As disclosed in our Form 10-K Goodwill
and Long-Lived Assets, page 34 “This growth relies upon the adoption and enforcement of environmental laws and regulations, particularly those that would require U.S. based coal fired electrical utilities to reduce the quantity of air
pollutants they release, including mercury, to comply with the Mercury and Air Toxics Standards that become effective in April 2015.”

2.
As a related matter, if any of your reporting units are at risk of failing step one of the impairment test (e.g. reporting units have estimated fair values that are not substantially in excess of the carrying value),
please revise your future filings to disclose the following:

•

The percentage by which fair value exceeded carrying value as of the date of your most recent goodwill impairment test;

•

The amount of goodwill allocated to the reporting unit;

•

A description of the methods and key assumptions used and how the key assumptions were determined;

•

A discussion of the degree of uncertainty associated with the key assumptions. The discussion regarding uncertainty should provide specifics to the extent possible (e.g., the valuation model assumes recovery from a
business downturn within a defined period of time); and

•

A description of potential events and/or changes in circumstances that could reasonably be expected to negatively affect the key assumptions.

 If you have determined that the estimated fair value substantially exceeds the carrying value for all of your
reporting units, please disclose this determination. Please refer to Item 303 of Regulation S-K and Sections 216 and 501.14 of the Financial Reporting Codification for guidance.

Cabot Response:

 The results of our most recent
goodwill impairment test indicated that the fair value of each of our four reporting units substantially exceeded the carrying value. The reporting unit with the most significant goodwill balance is Purification Solutions. As such, we disclose more
details around the assumptions used in its goodwill impairment test given its significance. In future filings, we will include substantially the following disclosure in our critical accounting policies “Goodwill and Long-Lived Assets” in
the MD&A section and our significant accounting policies footnote “Intangible Assets and Goodwill” (the new disclosures are underlined):

“… The fair value of a reporting unit is based on discounted estimated future cash flows. The assumptions used to estimate fair
value include management’s estimates of future growth rates, operating cash flows, capital expenditures, and discount rates over an estimate of the remaining operating period at the reporting unit level. Should the fair value of any of our
reporting units decline because of reduced operating performance, market declines, or other indicators of impairment, or as a result of changes in the discount rate, charges for impairment may be necessary. The future growth in the Purification
Solutions business, which had $[XXX] million of goodwill at [XXX], 2014, is highly dependent on the growth in the mercury removal portion of this business. This growth relies upon achieving the expected volumes and margins in the mercury
removal portion of this business and significantly depends on the adoption and enforcement of environmental laws and regulations, particularly those that would require U.S. based coal fired electrical utilities to reduce the quantity of air
pollutants they release, including mercury, to comply with the Mercury and Air Toxics Standards that become effective in April 2015. The annual review is performed as of May 31. Based on our most recent annual goodwill impairment test, the
fair values of all of our reporting units were substantially in excess of their carrying values…”

 Reinforcement Materials, page 46

3.
We note that the fiscal year 2013 decrease in Reinforcement Materials sales and EBIT were driven, in part, by lower prices, a less favorable product mix and lower volumes. Please show us how you will expand your
disclosures in future filings to explain the underlying causes of lower prices, a less favorable product mix and lower volumes. Please also consider discussing EBIT as a percentage of sales. Please address this comment as it relates to all your
segment sales and EBIT discussions.

 Cabot Response:

We have set forth below the discussion of the fiscal 2013 results of our Reinforcement Materials business, expanded to include a discussion of the underlying
causes of lower prices, a less favorable product mix and lower volumes (see underlined text). In future filings, we will expand our disclosure of our results to include more discussion of the underlying causes of changes in prices, product mix,
volumes and similar factors affecting results, as relevant, in our segment sales and EBIT discussions.

 “In fiscal 2013, sales in
Reinforcement Materials decreased by $117 million when compared to fiscal 2012. The decrease was principally driven by a less favorable price and product mix (combined $54 million), the unfavorable impact of foreign currency translation ($41
million), and 1% lower volumes ($23 million). The less favorable price and product mix was primarily due to price adjustments to customers for decreases in raw material costs and lower prices as a result of a more competitive market
environment in Asia and Europe. Lower volumes were primarily due to a weak economic environment in Europe and a supply disruption at one of our plants in Japan…

 …In fiscal 2013, Reinforcement Materials EBIT decreased by $39 million when compared to
fiscal 2012 driven principally by lower unit margins ($27 million) that resulted from lower prices and a less favorable product mix, lower volumes ($7 million), and higher fixed manufacturing costs ($7 million) primarily from higher utility costs.
Lower unit margins were driven by lower prices as a result of a more competitive market environment in Asia and Europe…”

 In response to
your comment to consider discussion of EBIT as a percentage of sales, we note that EBIT as a percentage of sales may be significantly affected by changes in net sales as a result of increases or decreases in prices based on the price adjustment to
customers for increases or decreases in raw material costs. Therefore, we do not include a discussion of EBIT as a percentage of sales because we do not believe it is an indicator of business performance. Instead we discuss changes in EBIT from
period to period which we believe is a better indicator of business performance.

 Form 10-Q for the Period Ended December 31, 2013

 Management’s Discussion and Analysis of Financial Condition and Results of Operations, page 32

Intangible Assets and Goodwill, page 33

4.
In your January 30, 2014 earnings call discussing results for the first quarter of fiscal 2014, Mr. Prevost indicated that the Purification Solutions segment “experienced another difficult quarter due
to lower volumes and operational issues.” In addition, he indicated that as a result of these operational issues, the Company needed to “reposition expectations for the 2014 Purification Solutions EBITDA performance.” Please tell us
how you considered ASC 350-20-35-30 in determining the need for an interim goodwill impairment evaluation for the Purification Solutions reporting unit in light of these adjusted performance expectations.

Cabot Response:

 In accordance with ASC
350-20-35-30, we determined that no events occurred or circumstances changed that would more likely than not reduce the fair value of the reporting unit below its carrying amount during the first quarter of fiscal 2014.

Although the results of the Purification Solutions segment in fiscal 2014 will not meet our initial expectations, we believe these results will be consistent
with fiscal 2013 results. Our expectations remain substantially unchanged for the future years in terms of growth and levels of profitability, notably in the mercury removal portion of this business, which we expect will contribute a significant
portion to the estimated future cash flows used in our impairment analysis. There have been no changes to the timing or substance of the Mercury and Air Toxics Standards regulation. We believe that the weaker than expected results in our
Purification Solutions business are mostly temporary in nature and not an indication of long term future cash flows used to determine the fair value of the reporting unit.

As requested, in connection with responding to the Staff’s comments, the Company hereby acknowledges that (i) the Company is responsible for the
adequacy and accuracy of the disclosure in its filings, (ii) Staff comments or changes to disclosure in response to Staff comments do not foreclose the Commission from taking any action with respect to the filing, and (iii) the Company may
not assert Staff comments as a defense in any proceeding initiated by the Commission or any person under the federal securities laws of the United States.

We would be happy to discuss any of our responses with you at your convenience. Please do not hesitate to call Jim Kelly, Cabot’s Controller, at
617-342-6020 with any questions concerning our financial statements, and Jane Bell, Cabot’s Corporate Secretary and Chief Counsel – Securities and Governance, at 617-342-6035 with any questions concerning legal matters.

Very truly yours,

 /s/ Eduardo E. Cordeiro

Eduardo E. Cordeiro

Executive Vice President and

Chief Financial Officer

Cc:
Patrick M. Prevost

Brian A. Berube

James P. Kelly

Jane A. Bell

Brian McAllister (Deloitte & Touche LLP)

March 7, 2014

Via E -mail
Eduardo E. Cordeiro
Chief Financial Officer
Cabot Corporation
Two Seaport Lane
Boston, MA  02210 -2019

Re: Cabot Corporation
 Form 10-K for the Fiscal Year Ended September 30, 2013
Filed November 27, 2013
Form 10 -Q for the Period Ended December 31, 2013
Filed February 6, 2014
File No. 1 -5667

Dear Mr. Cordeiro :

We have reviewed your filing an d have the following comments.  In some of our
comments, we may ask you to provide us with information so we may better understand your
disclosure.

Please respond to this letter within ten business days by prov iding the requested
information  or by advising us when you will provide the requested response.  If you d o not
believe our comments apply to your facts and circumstances or do not believe an amendment is
appropriate, please  tell us why in your response.

After reviewing the information you provide in response to these  comments, we may
have  additional commen ts.

Form 10 -K for the Fiscal Year Ended September 30, 2013

Management’s Discussion and Analysis…, page 32

Goodwill and Long -Lived Assets, page 34

1. You disclose on page 34 that your Purification Solutions business had goodwill of $466
millio n as of September 30, 2013 and that the growth of this reporting unit is highly
dependent on the growth in the mercury removal portion of this business.  Please tell us if
the estimated fair value of your Purification Solutions reporting unit substantially  exceed
the carrying value of this reporting unit as of your most recent goodwill impairment test.

Eduardo E. Cordeiro
Cabot Corporation
March 7, 2014
Page 2

 2. As a related matter, if any of your reporting units  are at risk of failing step one of the
impairment test (e.g. reporting units  have estimated fair values that are not substantially
in excess of the carrying value ), please  revise your future filings to  disclose the
following:
 The percentage by which fair value exceeded carrying value as of the date o f your
most recent goodwill impairment test ;
 The amount of  goodwill a llocated to the reporting unit;
 A description of the methods and key assumptions used and how the k ey assumptions
were determined;
 A discussion of the degree of uncertainty associated with the key assumptions. The
discussion regarding uncertainty should provide specifics to the extent possible (e.g.,
the valuation model assumes recovery from a business downturn within a defined
period  of time); and
 A description of potential events and/or changes in circumstances that could
reasonably be expected to negatively affect the key assumptions.
If you have determined that the estimated fair value substantially exceeds the carrying
value for  all of your reporting units, please disclose this determination.  Please refer to
Item 303 of Regulation S -K and Sections 216 and 501.14 of the  Financial Reporting
Codification for guidance.

Reinforcement Materials, page 46

3. We note that the fiscal year 2013 decrease in Reinforcement Materials sales and EBIT
were driven, in part, by lower prices, a less favorable product mix and lower volumes.
Please show us how you will expand your disclosures in future filings to explain the
underlying causes of lower prices, a less favorable product mix and lower volumes.
Please also consider discussing EBIT as a percentage of sales.  Please address this
comment as it relates to all your segme nt sales and EBIT d iscussions.

Form 10 -Q for the Period Ended December 31 , 2013

Management’s Discussion and Analysis of Financial Condition and Results of Operations, page
32

Intangible Assets and Goodwill, page 33

4. In your January 30, 2014 earnings call discussing results for the first quarter of fiscal
2014, Mr. Prevost indicated that the Purification Solutions segment “experienced another
difficult quarter due to lower volumes and operational issues.”  In addition,  he indicated
that as a result of these operational issues, the Company needed to “reposition
expectations for the 2014 Purification Solutions EBITDA performance .”  Please tell us
how you considered ASC 350 -20-35-30 in determining the need for an interim g oodwill
impairment evaluation for the Purification Solutions reporting unit in light of these
adjusted performance expectations.

Eduardo E. Cordeiro
Cabot Corporation
March 7, 2014
Page 3

We urge all persons who are responsible for the accuracy and adequacy of the disclosure
in the filing to be certain that the  filing includes the information the Securities Exchange Act of
1934 and all applica ble Exchange Act rules require.   Since the company and its management are
in possession of all facts relating to a company’s disclosure, they are responsible for the accura cy
and adequacy of t he disclosures they have made.

In responding to our comments, please provide  a written statement from the company
acknowledging that:

 the company is responsible for the adequacy and accuracy of the disclosure in the
filing;

 staff comments or changes to disclosure in response to staff comments do not
foreclose the Commission from taking any action with respect to the filing; and

 the company may not assert staff comments as a defense in any proceeding initiated
by the Commission or any person under the federal securities laws of the United
States.

You may contact Lisa Etheredge, Staff Accountant,  at (202) 551 -3424 or Jeanne Baker,
Assistant Chief Accountant, at (202) 551 -3691 if you have questions.

Sincerely,

 /s/ John Cas h

John Cash
Accoun ting Branch Chief

March 28 , 2013

Via E -mail
Eduardo E. Cordeiro
Executive Vice President and Chief Financial Officer
Cabot Corporation
Two Seaport Lane
Boston, MA  02210 -2019

Re: Cabot Corporation
 Form 10-K for the Year Ended September 30, 2012
Filed November 29, 2012
File No. 1 -5667

Dear Mr. Cordeiro :

We have completed our review of your filing .  We remind you that our comments or
changes to disclosure in response to our comments do not foreclose the Commission from taking
any action with respect to the company or the filing and the company may not assert staff
comments as a defense in any proceeding initiated by the Commission or any person under the
federal securities laws of the United  States.  We urge all persons who are responsible for the
accuracy and adequacy of the disclosure in the filing to be certain that the filing includes the
information the Securities Exchange Act of 1934 and all applicable rules require.

Sincerely,

 /s/ Rufus Decker

Rufu s Decker
Accounting Branch Chief

CORRESP
1
filename1.htm

Correspondence

 Date: March 25, 2013

Rufus Decker, Accounting Branch Chief

 Division
of Corporation Finance

 United States Securities and Exchange Commission

 Washington, D.C. 20549

Re:

Cabot Corporation

File No. 1-5667

 Dear Mr. Decker:

 This letter is being submitted in response to the Staff’s comment letter of March 15, 2013 in respect of Cabot Corporation’s response letter dated March 1, 2013. For ease of reference,
we have restated the Staff’s comments before our responses below.

 Form 10-K for the Year Ended September 30, 2012

 General

 1.
Where a comment below requests additional disclosures or other revisions to be made, please show us in your supplemental response what the revisions will look like. These revisions should be included in your future filings, including your interim
filings.

 Cabot Response:

 The following supplemental responses include disclosures that we propose to include in our next filing that requires such disclosures, which is our Form 10-Q for the quarter ending March 31, 2013.

 Item 8. Financial Statements and Supplementary Data, page 54

 Note M. Venezuela, page 83

 2. We note your response to comment six from our letter
dated February 15, 2013. On February 8, 2013, the Venezuelan government devalued its currency to an official rate of 6.3 bolivars fuerte (BsF) to the U.S. dollar from 4.3 BsF and announced that it is shutting down the SITME foreign
exchange system. Please address the following:

•

 Describe for us any instances in which you attempted to convert your bolivars into U.S. dollars and were unable to. Your response should
explain when the failed attempt (or attempts) was made, the amount you attempted to convert, and the reason why the attempt was unsuccessful; and

•

 Tell us if you performed an updated impairment analysis of your Venezuelan equity investment as a result of the recent currency devaluation.
If so, please advise us of the results of this analysis. If not, please tell us why you do not believe such an analysis was warranted.

 Cabot Response:

 We own 49% of an operating affiliate in Venezuela, which is
accounted for as an equity affiliate, through our wholly owned holding subsidiaries that carry the investment in the operating affiliate. These wholly owned holding subsidiaries receive dividends from the operating affiliate either in U.S. dollars
or in bolivars. As of February 28, 2013, these subsidiaries carried the operating affiliate investment of approximately $26 million, and held 20 million bolivars (approximately $3 million) in cash.

In response to the first part of the Staff’s comment, “Describe for us any instances in which you attempted to convert your bolivars into
U.S. dollars and were unable to. Your response should explain when the failed attempt (or attempts) was made, the amount you attempted to convert, and the reason why the attempt was unsuccessful”, in the past, we have attempted to
participate in Venezuelan government bond offerings, that would allow us to convert the bolivar cash held by our wholly owned holding subsidiaries to U.S. dollars.

The bond issuance process uses a bidding mechanism, where interested parties requiring U.S. dollars place a request for an amount of bonds in bolivars. The Venezuelan central bank
(“CADIVI”) determines the allocation of the bonds in that issuance across interested investors. We successfully converted 3.7 million bolivars to U.S. dollars through this process during fiscal year 2011. In addition, between August
2010 and October 2011, we made attempts to convert up to 17 million bolivars to U.S. dollars but did not receive an allocation to any bonds that were issued. There have not been any government bond or government-backed bond offerings since
October 2011.

 Our operating affiliate has significant export sales transactions denominated in U.S. dollars and may use a portion of these
dollars for payment of dividends. During fiscal year 2012, we were able to repatriate $6 million of dividends from our operating affiliate that were paid to our wholly owned holding subsidiaries using U.S. dollar cash provided from operations.

 With regard to the second part of the Staff’s comment, “Tell us if you performed an updated impairment analysis of your
Venezuelan equity investment as a result of the recent currency devaluation. If so, please advise us of the results of this analysis. If not, please tell us why you do not believe such an analysis was warranted”, in connection with the
recent currency devaluation, we performed an impairment analysis of our equity investment in Venezuela and determined the fair value of our investment using a discounted cash flow model, which included an analysis of the impact of the devaluation on
our operating affiliate’s profitability. We have also considered our ability to repatriate our share of the operating affiliate’s earnings. Based on our analysis, we determined that our equity investment is not impaired.

3. As a related matter, please consider revising your MD&A in future filings to address the following and show us what your future filing
disclosures will look like:

•

 Describe the timing and implications of the devaluation, from both an accounting and operational standpoint;

•

 Provide an estimate of the financial impact of the devaluation, including any gains or losses on monetary items or other-than-temporary
impairments on your equity method investment in Venezuela;

•

 Explain how the government actions regarding exchange rates and related restrictions have affected your ability to settle transactions and
repatriate cash;

•

 Discuss any changes in profitability related to the increase in the cost of imports and in-country sales prices of imported goods due to the
devaluation;

•

 Discuss any government pressures on vendors not to change sales prices and the expected effect on profitability after the devaluation;

•

 Describe any business practices or policies that have changed or are expected to change as a result of the devaluation; and

•

 If applicable, explain and quantify where possible the effect of the devaluation on your compliance with any debt covenants.

 Cabot Response:

 We have considered the following in determining our future disclosure that will be included in the MD&A section (note that the updated disclosure is shown at the bottom of this section):

From an accounting standpoint, the impact of the devaluation will be reflected in our consolidated financial statements for the second quarter ending
March 31 of fiscal 2013. Since Venezuela is considered a highly inflationary economy, the functional currency of our operating affiliate is the U.S. dollar. Therefore, the monetary assets and liabilities denominated in bolivars at our operating
affiliate were remeasured to reflect the currency devaluation. Our operating affiliate recognized a $1 million loss as a result of the remeasurement and a charge of $1 million to reflect the tax impact associated mainly with the revaluation of U.S.
dollar and Euro denominated cash and receivable balances for local tax purposes. Our share of these combined losses was approximately $1 million, which will be reflected in the equity in earnings of affiliated companies line of our consolidated
statements of operations for the

second quarter ending March 31 of fiscal 2013. In addition, we recorded a remeasurement loss of $1.5 million for cash denominated in bolivars held by our wholly owned holding subsidiaries,
which will be reflected in the other income (expense) line of our consolidated statements of operations for the second quarter ending March 31 of fiscal 2013. We are still evaluating any additional tax implications on our consolidated financial
statements and expect to recognize a tax benefit from a reduction in our deferred tax liability due to the impact of the devaluation of the bolivar on unremitted earnings. We also performed an impairment analysis in connection with the currency
devaluation to assess the recoverability of our equity investment in Venezuela. Based on our analysis, we determined that our equity investment is not impaired. It is worth noting that the devaluation does not have any effect on our compliance with
any debt covenants at either the operating affiliate or Cabot Corporation level.

 From an operational standpoint, we do not expect the
devaluation to have a significant impact on the results of our operating affiliate in Venezuela as more than half of its revenue relates to export sales, which are billed and collected in either U.S. dollars or Euros. In addition, our affiliate was
able to adjust prices for more than half of its domestic customers to mitigate some of the impact of the currency devaluation. It is our operating affiliate’s expectation that selling prices to substantially all of its domestic customers will
be adjusted in the current fiscal year as a result of the currency devaluation. In addition, our operating affiliate does not have a significant amount of imports. All products sold are manufactured locally and as such, raw materials purchases,
manufacturing costs, and operating expenses are denominated in bolivars.

 From governmental and regulatory standpoints, we are not aware of
any restrictions or government actions that would have a significant and adverse effect on our ability to settle transactions and repatriate cash. In addition, we are not currently aware of any government pressures that would limit our operating
affiliate’s ability to change sales prices of its products or of any changes or expected changes in business practices or policies as a result of the devaluation. As noted above, our affiliate was able to adjust prices for more than half of the
domestic customers to mitigate some of the impact of currency devaluation and expects to adjust selling prices to substantially all domestic customers in the current fiscal year.

 In future filings, we will include substantially the following discussion in our MD&A section (the new disclosures are underlined):

“We own 49% of an operating affiliate in Venezuela, which is accounted for as an equity affiliate, through wholly owned subsidiaries
that carry the investment and receive its dividends. As of March 31, 2013, these subsidiaries carried the operating affiliate investment of $XX million, and held XX million bolivars ($X million) in cash.

In February 2013, the Venezuelan government announced a devaluation of the bolivar from 4.3 bolivars to the U.S. dollar (B/$) to 6.3
B/$. Accordingly, we remeasured the bolivar denominated monetary accounts in our wholly owned subsidiaries at the new rate, resulting in the recognition of a $xx million loss in the second quarter of fiscal 2013 through other income (expense) within
the consolidated statements of operations. We also recognized a tax benefit of $xx million from a reduction in our deferred tax liability due to the impact of the devaluation of the bolivar on unremitted earnings. Our operating affiliate recognized
a $xx million loss in the second quarter of fiscal 2013 as a result of the remeasurement of monetary assets and liabilities in bolivars and a charge of $xx million from the tax impact of the currency devaluation mainly on U.S. dollar and Euro
denominated cash and receivable balances. Our share of these combined losses was approximately $xx million in the quarter ended March 31, 2013, which was included within the equity in earnings of affiliated companies line of our consolidated
statements of operations.

 As a result of the currency devaluation, we performed an impairment analysis on our equity
investment in Venezuela during the second quarter of fiscal 2013 using the discounted cash flow model to determine the fair value of our investment. We determined that there was no impairment to the carrying value of our equity investment. We
currently believe that the devaluation of the bolivar will not have a significant adverse impact on our affiliate’s ongoing operations, the operating affiliate will continue to be profitable, and we will still be able to repatriate earnings
from this affiliate in the future. We continue to closely monitor developments in Venezuela and their potential impact on the recoverability of our equity affiliate investment.

During the six months ended March 31, 2013 and 2012, the operating affiliate declared dividends of xx million bolivars and xx
million bolivars, respectively, to our wholly owned subsidiaries, which were paid in U.S. dollars at an exchange rate of 4.30 bolivars. We repatriated $xx million and $xx million from our wholly owned subsidiaries in the quarters ended
March 31, 2013 and 2012, respectively, and $xx million and $xx million in the six months ended March 31, 2013 and 2012, respectively.

 The Venezuelan bolivars held by our wholly owned subsidiaries may only be exchanged
for foreign currencies through certain Venezuelan government controlled channels. The channels available are the Venezuelan central bank (“CADIVI”), and Venezuelan government and government-backed bond offerings. The bond offerings use a
bidding process, where companies and individuals requiring U.S. dollars place a request for a fixed sum, and CADIVI then determines how to allocate the pool of U.S. dollars in that issuance. We closely monitor our ability to convert our bolivar
holdings into U.S. dollars, as we still intend to convert substantially all bolivars held by our wholly owned subsidiaries in Venezuela to U.S. dollars as soon as practical. Any future change in the CADIVI official rate or opening of
additional parallel markets could lead us to change the exchange rate and result in gains or losses on our bolivar denominated assets held by our subsidiaries.”

 Note V. Financial Information by Segment & Geographic Area, page 106

 4. We
note your response to comment eight from our letter dated February 15, 2013. It appears that the reported revenues for your Specialty Carbons and Compounds operating segment were greater than 10 percent of the combined revenue for all your
operating segments for all periods presented. As such, please tell us how you considered ASC 280-10-50-10 and 50-12 in determining that the Specialty Carbons and Compounds operating segment should not be separately presented as its own reportable
segment.

 Cabot Response:

 As noted in our response to comment eight dated March 1, 2013, Specialty Carbon and Compounds and Fumed Metal Oxides operating segments are aggregated into a single operating segment (Performance
Materials) as they are similar in terms of economic characteristics, nature of products, processes, customer class and product distribution methods in accordance with ASC 280-10-50-10 and 50-11. Because the Specialty Carbon and Compounds and Fumed
Metal Oxides operating segments are aggregated into the Performance Materials operating segment, the quantitative thresholds described in ASC 280-10-50-12 were analyzed at the Performance Materials segment level. Reported revenue, profit, and assets
of the Performance Materials segment were greater than 10 percent of the combined revenue, profit, and assets for all operating segments for all periods presented and as such it was presented as its own reportable segment in accordance with ASC
280-10-50-10 to 50-12.

 As requested, in connection with responding to the Staff’s comments, the Company hereby acknowledges that the
Company is responsible for the adequacy and accuracy of the disclosure in its filings, Staff comments or changes to disclosure in response to Staff comments do not foreclose the Commission from taking any action with respect to the filing, and the
Company may not assert Staff comments as a defense in any proceeding initiated by the Commission or any person under the federal securities laws of the United States.

 We would be happy to discuss any of our responses with you at your convenience. Please do not hesitate to call Jim Kelly, Cabot’s Controller, at 617-34

March 15 , 2013

Via E -mail
Eduardo E. Cordeiro
Executive Vice President and Chief Financial Officer
Cabot Corporation
Two Seaport Lane
Boston, MA  02210 -2019

Re: Cabot Corporation
 Form 10-K for the Year Ended September 30, 2012
Filed November 29, 2012
Response Dated March 1, 2013
File No. 1 -5667

Dear Mr. Cordeiro :

We have reviewed your response letter dated March 1, 2013  and have the following
comments.  In some of our comments, we may ask you to provide us with information so we
may better understand your disclosure.

Please respond to this letter within ten business days by prov iding the requested
information  or by advising us when you will provide the requested respon se.  If you do not
believe our comments apply to your facts and circumstances, please tell us why in your response.

After reviewing the information you provide in response to these  comments, we may
have  additional comments.

General

1. Where a comment below requests additional disclosures or other revisions to be made, please
show us in your supplemental response what the revisions will look like.  These revisions
should be included in your future filings, including your interim filings.

Item 8. Financial Statements and Supplementary Data, page 54

Note M. Venezuela, page 83

2. We note your response to comment six from our letter dated February 15, 2013.  On
February 8, 2013, the Venezuelan government devalued its currency to an official rate of  6.3
bolivars fuerte (BsF) to the U.S. dollar from 4.3 BsF and announced that it is shutting down
the SITME foreign exchange system.  Please address the following:
 Describe for us any instances in which you attempted to convert your bolivars into U.S.
dollars and were unable to.  Your response should explain when the failed attempt (or

Eduardo E. Cordeiro
Cabot Corporation
March 15 , 2013
Page 2

 attempts) was made, the amount you attempted to convert, and the reason w hy the
attempt was unsuccessful; and
 Tell us if you performed an updated impairment analysis of your  Venezuelan equity
investment as a result of the recent currency devaluation.  If so, please advise us of the
results of this analysis.  If not, please tell us why you do not believe such an analysis was
warranted.

3. As a related matter, please consider re vising your MD&A in future filings to address the
following and show us what your future filing disclosures will look like:
 Describe the timing and implications of the devaluation, from both an accounting and
operational standpoint;
 Provide an estimate of the financial impact of the devaluation, including any gains or
losses on monetary items or other -than-temporary impairments on your equity method
investment in Venezuela;
 Explain how the government actions regarding exchange rates and related restrictions
have affected your ability to settle transactions and repatriate cash;
 Discuss any changes in profitability related to the increase in the cost of imports and in -
country sales prices of imported goods due to the devaluation;
 Discuss any government pressures on vendors not to change sales prices and the expected
effect on profitability after the devaluation;
 Describe any business practices or policies that have changed or are expected to change
as a result of the devaluation; and
 If applicable, explain and quantify where possible the effect of the devaluation on your
compliance with any debt covenants.

Note V. Financial Information by Segment & Geographic Area, page 106

4. We note your response to comment eight from our letter dated February 15, 2013.  It appears
that the reported revenues for your Specialty Carbons and Compounds operating segment
were greater than 10 percent of the combined revenue for all your operating seg ments for all
periods presented.  As such, please tell us how you considered ASC 280 -10-50-10 and 50 -12
in determining that the Specialty Carbons and Compounds operating segment should not be
separately presented as its own reportable segment.

You may co ntact Lisa Etheredge, Staff Accountant,  at (202) 551 -3424 or Jeanne Baker,
Assistant Chief Accountant,  at (202) 551 -3691 .

Sincerely,

 /s/ Rufus Decker

Rufus Decker
Accounting Branch Chief

CORRESP
1
filename1.htm

SEC Response Letter

 March 1, 2013

 Rufus Decker, Accounting Branch Chief

 Division of Corporation Finance

United States Securities and Exchange Commission

Washington, D.C. 20549

Re:
Cabot Corporation

 File
No. 1-5667

 Dear Mr. Decker:

 This letter is being submitted in response to the Staff’s comment letter of February 15, 2013 in respect of Cabot Corporation’s Form 10-K for the fiscal year ended September 30, 2012.
For ease of reference, we have restated the Staff’s comments before our responses below.

 Form 10-K for the Year Ended
September 30, 2012

 General

 1. Where a comment below requests additional disclosures or other revisions to be made, please show us in your supplemental response what the revisions will look like. These revisions should be
included in your future filings, including your interim filings.

 Cabot Response:

The following supplemental responses include disclosures that we propose to include in our next filing that requires such disclosures which is our Form
10-Q for the quarter ended March 31, 2013.

 Item 7. Management’s Discussion and Analysis of Financial Condition and Results
of Operations, page 31

 Critical Accounting Policies, page 31

 Goodwill and Long-Lived Assets, page 33

 2. Please expand your disclosures to clarify
the level at which you determine your reporting units and describe how you determined them. Specifically address if the businesses underlying your Performance Material and Advanced Technologies business segments are reporting units. Refer to ASC
350-20-35-33 through 37 and ASC 350-20-55-1 through 55-9.

 Cabot Response:

In future filings, we will expand our disclosure in the Goodwill and Long-Lived Assets section of our Critical Accounting Policies to include
substantially the following disclosure (the addition to the existing disclosure is underlined):

 “Goodwill is not amortized but is
reviewed for impairment annually, or when events or changes in the business environment indicate that the carrying value of the reporting unit may exceed its fair value. A reporting unit, for the purpose of the impairment test, is at or below the
operating segment level, and constitutes a business for which discrete financial information is available and regularly reviewed by segment management. The separate businesses included within the Performance Materials and Advanced Technologies
business segments are considered separate reporting units. Goodwill balances relative to these segments are recorded in the Fumed Metal Oxides reporting unit within Performance Materials and the Security Materials reporting unit within Advanced
Technologies.”

 3. Please expand your disclosures regarding impairment of long-lived assets to address how you group long-lived
assets for impairment and your basis for that determination.

 Cabot Response:

 In future filings, we will expand our disclosure in the Goodwill and Long-Lived Assets section of our Critical Accounting Policies to substantially read as follows (the addition to the existing disclosure
is underlined):

 “To test for impairment of assets we generally use a probability-weighted estimate of the future undiscounted net cash
flows of the assets over their remaining lives to determine if the value of the asset is recoverable. Long-lived assets are grouped with other assets and liabilities at the lowest level for which independent identifiable cash flows are
determinable.”

 Results of Operations, page 38

 Provision for Income Taxes, page 41

 4. You disclose on page 38 that your non-GAAP
measure “operating tax rate” excludes discrete tax items, which are unusual or infrequent items, and the impact of certain items on both operating income and the tax provision. Please reconcile your effective tax rate to your operating tax
rate and provide a statement disclosing the reasons why management believes that presentation of this non-GAAP financial measure provides useful information to investors. Refer to Item 10(e)(1)(i)(A) and (B) of Regulation S-K.

 Cabot Response:

In our discussion of Cabot’s tax rate, we utilize a non-GAAP measure which we refer to as our “operating tax rate”. The operating tax rate
measure excludes the tax impact of the certain items as defined on page 38 in the Definition of Terms and Non-GAAP Financial Measures section, and discrete tax items which include: i) items that management considers to be unusual or infrequent (such
as the release of state tax valuation allowances in 2012 and the repatriation of high taxed earnings in response to changes in U.S. legislation in 2011), ii) items relating to uncertain tax positions (such as tax audit settlements, interest on tax
reserves and the release of tax reserves from the expirations of statute of limitations), and iii) other discrete tax items (such as the retroactive renewal of the U.S. research and experimentation credit in 2011 and tax rate changes in foreign
jurisdictions enacted in 2012).

 Management believes that this non-GAAP financial measure is useful supplemental information because it helps
our investors compare our tax rate year to year on a consistent basis and understand what our tax rate on current operations would be without the impact of these items which we do not believe are reflective of the underlying business results. A
reconciliation of the operating tax rate to the effective tax rate, its most comparable GAAP financial measure, is shown below.

Provision for Income Taxes and Reconciliation of Non-GAAP Measure

Years Ended September 30

2012

2011

2010

 Provision for income taxes

$
55

$
6

$
30

 Effective tax rate

22
%

3
%

18
%

 Impact of discrete tax items:

 Unusual or infrequent items

3
%

12
%

1
%

 Items related to uncertain tax positions

—
%

7
%

8
%

 Other discrete tax items

1
%

1
%

—
%

 Impact of certain items

(1
%)

(1
%)

(2
%)

 Operating tax rate

25
%

22
%

25
%

 In future Form 10-Q and Form 10-K filings we will replace the Provision for Income Taxes table on page 41
with the above table which has been expanded to include the reconciliation of our effective tax rate to our operating rate. We will also revise the tax discussion in the “Definition of Terms and Non-GAAP Financial Measures” section on page
38 in future Form 10-K filings as follows:

 “The discussion under the heading “Provision for Income Taxes and Reconciliation of
Non-GAAP Measure” includes a discussion of our “effective tax rate” and our “operating tax rate” and includes a reconciliation of the two rates. Our operating tax rate is a non-GAAP financial measure and should not be
considered an alternative to our effective tax rate, the most comparable GAAP financial measure. In calculating our operating tax rate, we exclude discrete tax items, which include: i) unusual or infrequent items such as a significant release of a
valuation allowance, ii) items related to uncertain tax positions such as the tax impact of audit settlements, interest on tax reserves, and the release of tax reserves from the expiration of statutes of limitations, and iii) other discrete tax
items such as the tax impact of legislative changes. We also exclude the tax impact of certain items, as defined below in the discussion of Total Segment EBIT, on both operating income and the tax provision. Our definition of the operating tax rate
may not be comparable to the definition used by other companies.

 Management believes that this non-GAAP financial measure is useful
supplemental information because it helps our investors compare our tax rate year to year on a consistent basis and understand what our tax rate on current operations would be without the impact of these items which we do not believe are reflective
of the underlying business results.”

 In future Form 10-Q filings, the discussion above will be included with some minor revisions to
account for two additional items excluded from the operating tax rate during the quarters when applicable: the impact of the timing of losses for which there is no tax benefit and the cumulative adjustment to our estimated annual effective tax rate
recorded in the quarter.

 Item 8. Financial Statements and Supplementary Data, page 54

Note M. Venezuela, page 83

 5. We note
that given the uncertainties around the convertibility of the Venezuelan bolivar to the U.S. dollar and the ability of entities to actually repatriate U.S. dollars from Venezuela, the Company has endeavored, whenever possible, to repatriate the
Company’s cash from its Venezuelan subsidiaries using available mechanisms. Please tell us and clarify in future filings whether the Company has been able to repatriate such cash during the periods presented and, if so, quantify the amounts
repatriated.

 Cabot Response:

 We repatriated $6 million, $2 million, and no cash from our Venezuelan subsidiaries in our fiscal years ended 2012, 2011 and 2010, respectively. In addition, we repatriated $4 million of cash from the
subsidiaries in the first quarter of fiscal 2013. In future filings, we will include the following discussion in our Venezuela footnote to disclose the cash repatriated from our Venezuelan subsidiaries:

“The Company repatriated $xxx million, $xxx million and $xxx million from its Venezuela subsidiaries in the quarters/fiscal years ended
December 31/March 31/June 30/September 30 20xx, 20xx and 20xx, respectively.”

 6. We note that management has closely monitored its investment in the operating affiliate in Venezuela
to ensure that the investment continues to be recoverable and that you still intend to convert substantially all bolivars held by its Venezuelan subsidiaries to U.S. dollars as soon as practical. In light of your recent ability or inability to
repatriate cash from these subsidiaries, please tell us and expand your disclosures in future filings to clarify how you have determined that your investment is recoverable.

 Cabot Response:

 We utilize a discounted cash flow model to determine if investments
are impaired when triggering events occur that suggest that our investment may be subject to an other-than-temporary decline in value. Based on the profitability of our operating affiliate in Venezuela and our anticipated ability to continue to
repatriate its earnings, we have determined that our investment in the affiliate is recoverable and no events have occurred that indicate an other-than-temporary decline in the investment value.

In future filings, we will include substantially the following discussion in our Venezuela footnote to disclose how we have determined that our
investment in the Venezuelan affiliate is recoverable:

 “The Company continues to monitor developments in Venezuela and their potential
impact on the Company’s investment. Cabot uses a discounted cash flow model to determine if investments are impaired when events may indicate that an other-than-temporary decline in investment value has occurred. Based on the profitability of
the operating affiliate and our ability to repatriate cash from this affiliate in recent years and our anticipated ability to repatriate earnings in the future, the Company does not believe that the investment in the operating affiliate is
impaired.”

 Note T. Commitments and Contingencies, page 102

 7. We note your disclosure on page 103 that the $7 million reserve for environmental matters represents your current best estimate of costs likely to be incurred for remediation. If there is at least a
reasonable possibility that a loss exceeding amounts already recognized may have been incurred for any of your environmental proceedings, please revise to either disclose an estimate of the additional loss or range of loss, or state that such an
estimate cannot be made. If you have not disclosed an estimate because the amount is immaterial, please disclose that fact in lieu of providing quantified amounts. Please refer to ASC 450-20-50.

Cabot Response:

 In future
filings we will include substantially the following discussion in our Commitments and Contingencies footnote (revisions to the existing disclosure are marked):

 “As of December 31, 2012 and September 30, 2012, Cabot had $6 million and $7 million, respectively, on a discounted basis ($7 million on an undiscounted basis at both December 31, 2012
and September 30, 2012), reserved for environmental matters primarily related to divested businesses. These amounts represent Cabot’s best estimates of its share of the probable costs likely to be incurred by Cabot
at those sites where costs are reasonably estimable based on its analysis of the extent of clean up required, alternative clean up methods available, abilities of other responsible parties to contribute and its interpretation of laws and regulations
applicable to each site. Cabot reviews the adequacy of this reserve as circumstances change at individual sites. Cash payments related to these environmental matters were less than $1 million in the first three months of both fiscal
2013 and 2012. Cabot reviews the adequacy of the reserve as circumstances change at individual sites. Almost all of our reserves relate to environmental issues that are mature and have been investigated and studied and, in many cases, are subject
to agreed upon remediation plans. However, depending on the results of future testing, changes in risk assessment practices, remediation techniques and regulatory requirements, newly discovered conditions, and other factors, it is reasonably
possible that we could incur additional costs in excess of environmental reserves currently recorded. Management estimates, based on the latest available information, that any such future environmental remediation costs in excess of amounts already
recorded would be immaterial to the Company’s consolidated financial statements.

 Note V. Financial Information by Segment & Geographic Area, page 106

8. You identify four business segments: Reinforcement Materials, Performance Materials, Advanced Technologies, and Purification Solutions. Performance
Material is comprised of two businesses: Specialty Carbons and Compounds and Fumed Metal Oxides. Advanced Technologies is comprised of five businesses: Inkjet Colorants, Aerogel, Security Materials, Elastomer Composites and Specialty Fluids. We have
the following comments in this regard:

•

 Please tell us how you considered if these businesses are operating segments as defined by ASC 280-10-50;

•

 Please revise your accounting policy to clarify how you identified your operating segments. Specifically, please clarify the level at which your
chief operating decision maker (CODM) receives financial information for purposes of making decisions about the allocation of resources and evaluating performance; and

•

 If you are aggregating any operating segments into reportable segments, please disclose this fact in accordance with ASC 280-10-50-21a and provide
disclosures that confirm the aggregated operating segments all have similar economic characteristics in addition to similar products and services, processes, customers, distribution channels, and regulatory environments. Please refer to ASC
280-10-50-11 for guidance.

 Cabot Response:

 In response to the first part of the Staff’s comment to “Please tell us how you considered if these businesses are operating segments as defined by ASC 280-10-50”, we advise that we
have identified our operating segments by applying the criteria of ASC 280-10-50-1. We have determined that all of our businesses are operating segments as each of these businesses engages in commercial activity, earns revenues and incurs expenses
and discrete financial information is available at the business level. The CODM regularly reviews a package that includes discrete financial information for each of the operating segments. Primarily, the CODM uses earnings before income taxes to
evaluate the operating results of each operating segment, allocate resources and make other decisions on business operations and strategy.

 In
r

February 15, 2013

Via E -mail
Eduardo E. Cordeiro
Executive Vice President and Chief Financial Officer
Cabot Corporation
Two Seaport Lane
Boston, MA  02210 -2019

Re: Cabot Corporation
 Form 10-K for the Year Ended September 30, 2012
Filed November 29, 2012
File No. 1 -5667

Dear Mr. Cordeiro :

We have reviewed your filing an d have the following comments.  In some of our
comments, we may ask you to provide us with information so we may better understand your
disclosure.

Please respond to this letter within ten business days by prov iding the requested
information  or by advising us when you will provide the requested response.   If you do not
believe our comments apply to your facts an d circumstances, please tell us why in your response.

After reviewing the information you provide in response to these  comments, we may
have  additional comments.

General

1. Where a comment below requests additional disclosures or other revisions to be made, please
show us in your supplemental response what the revisions will look like.  These revisions
should be included in your future filings, including your interim filings.

Item 7. Management’s Discussion and Analysis of Financial Con dition and Results of
Operations, page 31

Critical Accounting Policies, page 31

Goodwill and Long -Lived Assets, page 33

2. Please expand your disclosures to clarify the level at which you determine your reporting
units and describe how you determined them.   Specifically address if the businesses

Eduardo E. Cordeiro
Cabot Corporation
February 15, 2013
Page 2

 underlying your Performance Material and Advanced Technologies business segments are
reporting units.  Refer to ASC 350 -20-35-33 through 37 and ASC 350 -20-55-1 through 55 -9.

3. Please expand your disclosures regardi ng impairment of long -lived assets to address h ow you
group long -lived assets for impairment and your basis for that determination .

Results of Operations, page 38

Provision for Income Taxes, page 41

4. You disclose on page 38 that your non -GAAP measure “ operating tax rate ” exclude s discrete
tax items, which are unusual or infrequent items, and the impact of certain items on both
operating income and the tax provision.  Please reconcile your effective tax rate to your
operating tax rate and provide a  statement disclosing the reasons why management b elieves
that presentation of this  non-GAAP financial measure provides useful information to
investors .  Refer to Item 10(e)(1)(i)(A) and (B) of Regulation S -K.

Item 8. Financial Statements and Supplementary Data , page 54

Note M. Venezuela, page 83

5. We note that g iven the uncertainties around the convertibility of the Venezuelan bolivar to
the U.S. dollar and the ability of entities to actually repatriate U.S. dollars from Venezuela,
the Company has  endeavored, w henever possible, to repatriate the Company’s cash from its
Venezuelan subsidiaries using available mechanisms. Please tell us and clarify in future
filings whether the Company has been able to repatriate such cash during the periods
presented and, if so, quantify the amounts repatriated.

6. We note that  management has closely monitored its investment in the operating affiliate in
Venezuela to ensure that the investment continues to be recoverable  and that you still intend
to convert substantially all boliv ars held by its Venezuelan subsidiaries to U.S. dollars as
soon as practical .  In light of your recent ability or inability to repatriate cash from these
subsidiaries, please tell us and expand your disclosures in future filings to clarify how you
have det ermined that your investment is recoverable.

Note T. Commitments and Contingencies, page 102

7. We note your disclosure on page 103 that the $7 million reserve for environmental matters
represents your current best estimate of costs likely to be incurred for remediation.  If there is
at least a reasonable possibility that a loss exceeding amounts already recognized may have
been incurred for any of your environmental proceedings, please revise to either disclose an
estimate of the additional loss or range of loss, or state that such an estimate cannot be made.
If you have not disclosed an estimate because the amount is immaterial, please disclose that
fact in lieu of providing quantified amounts.  Please refer to ASC 450 -20-50.

Eduardo E. Cordeiro
Cabot Corporation
February 15, 2013
Page 3

Note V. Financial Informat ion by Segment & Geographic Area, page 106

8. You identify four business segments : Reinforcement Materials , Performan ce Materials,
Advanced Technologies,  and Purification Solutions.   Performance Material is comprised of
two businesses: Specialty Carbons and Compounds and Fumed Metal Oxides.  Advanced
Technologies is comprised of five businesses:  Inkjet Colorants, Aerogel, Security Materials,
Elastomer Composites and Specialty Fluids.  We have the following comments in this regard:
 Please tell us how you cons idered if these businesses are operating segments as defined
by ASC 280 -10-50;
 Please revise your accounting policy to clarify how you identified your operating
segments.   Specifically, please clarify the level at which your chief operating decision
maker (CODM) receives financial information for purposes of making decisions about
the allocation of resources and evaluating performance; and
 If you are aggregating any operating segments into reportable segments, please disclose
this fact in accordance with A SC 280 -10-50-21a and provide disclosures that confirm the
aggregated operating segments all have similar economic characteristics in addition to
similar products and services, processes, customers, distribution channels, and regulatory
environments.  Pleas e refer to ASC 280 -10-50-11 for guidance.

We urge all persons who are responsible for the accuracy and adequacy of the disclosure
in the filing to be certain that the filing includes the information the Securities Exchange Act of
1934 and all applicabl e Exchange Act rules require.   Since the company and its management are
in possession of all facts relating to a company’s disclosure, they are responsible for the accuracy
and adequacy of the disclosures they have made.

 In responding to our comments, please provide  a written statement from the company
acknowledging that:
 the company is responsible for the adequacy and accuracy of the disclosure in the filing;
 staff comments or changes to disclosure in response to staff comments do not foreclose
the Com mission from taking any action with respect to the filing; and
 the company may not assert staff comments as a defense in any proceeding initiated by
the Commission or any person under the federal securities laws of the United States.

You may contact Lisa Etheredge, Staff Accountant,  at (202) 551 -3424 or Jeanne Baker,
Assistant Chief Accountant,  at (202) 551 -3691 .

Sincerely,

 /s/ Rufus Decker

Rufus Decker
Accounting Branch Chief

March 9, 2012
 Via E-mail

Mr. Eduardo Cordeiro Executive Vice President and Chief Financial Officer Cabot Corporation Two Seaport Lane, Suite 1300 Boston, MA  02210
RE: Cabot Corporation
Form 10-K for the Year ended September 30, 2011
Filed November 29, 2011
  File No. 1-5667

Dear Mr. Cordeiro:
We have completed our review of your f ilings.  We remind you that our comments or
changes to disclosure in res ponse to our comments do not for eclose the Commission from taking
any action with respect to the company or the filings and the company may not assert staff
comments as a defense in any proceeding ini tiated by the Commission or any person under the
federal securities laws of the United States.  We urge all pers ons who are responsible for the
accuracy and adequacy of the disclosure in the fi lings to be certain that the filings include the
information the Securities Exchange Act of 1934 and all applicable rules require.
 Sincerely,

 /s/ Rufus Decker
  Rufus Decker
Accounting Branch Chief

CORRESP
1
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SEC Comment Letter

 February 29, 2012

 Rufus Decker, Accounting Branch Chief

 Division of Corporation Finance

United States Securities and Exchange Commission

Washington, D.C. 20549

Re:
Cabot Corporation

File No. 1-5667

 Dear Mr. Decker:

 This letter is being submitted in response to the Staff’s comment letter of February 15, 2012 in respect of Cabot
Corporation’s Form 10-K for the fiscal year ended September 30, 2011 and Form 10-Q for the quarter ended December 31, 2011. For ease of reference, we have restated the Staff’s comments before our responses below.

Form 10-K for the Year Ended September 30, 2011

 Item 7 – Management’s Discussion and Analysis of Financial Condition and Results of Operations, page 30

 Results of Operations, page 37

1.
You present total segment EBIT on page 42. Since total segment EBIT represents a non-GAAP measure when it is presented or discussed outside of your SFAS 131
footnote, in future filings you should ensure either:

 (a) Total segment EBIT is not presented outside of
your SFAS 131 footnote or

 (b) If you choose to present total segment EBIT outside of your SFAS 131, you must include
all the disclosures required by Item 10(e) of Regulation S-K including the following:

•

 reconcile from total segment EBIT to income (loss) from continuing operations before taxes and then on to net income to highlight the differences
between the non-GAAP measure and operating income,

•

 identify this amount as a non-GAAP performance measure,

•

 state the material limitations associated with use of the non-GAAP financial measure as compared to the use of the most directly comparable GAAP
financial measure,

•

 state the manner in which management compensates for these limitations when using the non-GAAP financial measure,

•

 explain why your management believes that this measure provides useful information to investors,

•

 state how your management uses the non-GAAP measure,

•

 provide cautionary disclosure that the non-GAAP measure presented may not be comparable to similarly titled measures used by other entities
and

•

 state that this non-GAAP measure should not be considered as an alternative to net income, which is determined in accordance with GAAP.

 See also Question 104.04 of the SEC Compliance and Disclosure Interpretations: Non-GAAP Financial Measures. Please show
us in your supplemental response what the revisions will look like.

 Cabot Response:

In future filings, we will expand upon the “Definition of Terms” within the existing first paragraph on page 37 of our 10-K to substantially
read as follows:

 “Total Segment EBIT. The following discussion of results includes information on our
reportable segment sales and segment (or business) operating profit (loss) before interest and tax (“segment EBIT”). Total Segment EBIT is a non-GAAP performance measure, and should not be considered an alternative for

Income (loss) from continuing operations before taxes, the most directly comparable GAAP financial measure. In calculating total segment EBIT, we exclude “certain items”, meaning items
that management does not consider representative of our fundamental segment results, as well as items that are not allocated to our business segments, such as interest expense and other corporate costs. Our Chief Operating Decision Maker uses
segment EBIT to evaluate the operating results of each segment and to allocate resources to the segments. We believe that this non-GAAP measure provides useful supplemental information for our investors as it is an important indicator of the
Company’s operational strength and performance. Investors should consider the limitations associated with this non-GAAP measure, including the potential lack of comparability of this measure from one company to another. A reconciliation of
total segment EBIT to Income (loss) from continuing operations before income taxes and equity in net earnings of affiliated companies is set forth within this section.”

 The table included on page 42 of our 10-K reconciles total segment EBIT to Income (loss) from continuing operations before taxes which is the most directly comparable GAAP financial measure. There are no
further non-GAAP differences between Income (loss) from continuing operations before taxes and Net Income.

 Item 8 – Financial
Statements and Supplementary Data, page 54

 Note A – Significant Accounting Policies, page 62

General

2.
Please disclose in future filings the types of expenses that you include in the cost of sales line item and the types of expenses that you include in the selling and
administrative expenses line item. Please also disclose whether you include inbound freight charges, purchasing and receiving costs, inspection costs, warehousing costs, internal transfer costs, and the other costs of your distribution network in
the cost of sales line item. With the exception of warehousing costs, if you currently exclude a portion of these costs from cost of sales, please disclose:

•

 in a footnote the line items that these excluded costs are included in and the amounts included in each line item for each period presented, and

•

 in MD&A that your gross margins may not be comparable to those of other entities, since some entities include all of the costs related to their
distribution network in cost of sales and others like you exclude a portion of them from gross margin, including them instead in a line item such as selling and administrative expenses.

Please show us in your supplemental response what the revisions will look like.

 Cabot Response:

 We confirm that we include the items listed in the Staff’s
comment within cost of sales, therefore, the additional supplemental disclosures suggested in the comment would not be required. In future filings, we will include substantially the following discussion in our Significant Accounting Policies Note to
disclose the types of expenses included in the cost of sales and selling and administrative expense line items:

 “Cost of Sales

 Cost of sales consists of the cost of raw and packaging materials, direct manufacturing costs, depreciation, internal transfer costs,
inspection costs, inbound and outbound freight and shipping and handling costs, plant purchasing and receiving costs and other overhead expense necessary to manufacture the products.

 Selling and Administrative Expenses

 Selling and administrative expenses consist of salaries and fringe benefits of sales and office personnel, general office expenses and other expenses not directly related to manufacturing
operations.”

 Inventories, page 62

3.
You use both the average cost and FIFO methods to determine the cost of your inventories for all non-U.S. inventories and certain U.S. inventories. You should
generally use one inventory method for similar types of inventories. Please disclose in future filings which types of inventory you use each method for, and disclose whether you use both methods for any similar types of inventory. If so, please also
disclose your basis for doing this. Please show us in your supplemental response what the revisions will look like.

Cabot Response:

 In our
Significant Accounting Policies Note on page 62 of our Form 10-K, under Inventories, we disclosed that we use the LIFO method to account for most of our U.S. inventories. The LIFO methodology is used for our U.S. carbon black inventories. Cabot uses
the average cost method for Specialty Fluids inventories and the FIFO method to determine the cost of inventories for all other U.S. and non-U.S. inventories. In future filings, we will include substantially the following discussion in our
Inventories section of our Significant Accounting Policies Note:

 “Inventories are stated at the lower of cost or market. The cost of all
U.S. carbon black inventories is determined using the last-in, first-out (“LIFO”) method. The cost of Specialty Fluids inventories is determined using the average cost method. The cost of other U.S. and all non-U.S. inventories is
determined using the first-in, first-out (“FIFO”) method.”

 Note S – Income Taxes, page 97

4.
We note that you repatriated $24 million of high tax income in response to recent changes in U.S. tax legislation. Please tell us and revise your disclosure in
future filings to address how you concluded, in light of your repatriation, that you have the ability and intent to invest $887 million of undistributed earnings of non-U.S. subsidiaries indefinitely as of September 30, 2011. Please refer to
ASC 740-30-25-17 though 19.

 Cabot Response:

 The repatriation referred to in our Form 10-K was made prior to the effective date of a change in tax law in order to preserve a significant tax benefit. It was a one-time event and is not indicative of
our overall reinvestment plans and repatriation practices. Generally, cash generated from operations outside the U.S. has been used to fund growth in our non-U.S. operations and has not been repatriated to the U.S. as there has been no need to move
cash to the U.S. We expect that these circumstances, both our cash needs in the U.S. and our intent to continue to invest our foreign earnings designated as indefinitely reinvested, to continue for the foreseeable future.

In future filings, we will expand upon the discussion of our reinvestment of undistributed earnings of non-U.S. subsidiaries, in substance as follows:

 “As of September 30, 20xx, provisions have not been made for U.S. income taxes or non-U.S. withholding taxes on approximately $xxx
million of undistributed earnings of non-U.S. subsidiaries, as these earnings are considered indefinitely reinvested. Cabot continually reviews the financial position and forecasted cash flows of all its subsidiaries both within and outside the U.S.
in order to reaffirm the Company’s intent and ability to continue to indefinitely reinvest earnings of these foreign subsidiaries or whether such earnings will need to be repatriated in the foreseeable future. Such review encompasses not only
operational needs but also future capital investments. From time to time, however, our intentions relative to specific indefinitely reinvested amounts do change because of certain unique circumstances. For example, in 2011, the Company did remit
certain high taxed earnings that had previously been considered indefinitely reinvested in order to preserve a tax benefit in advance of a tax law change.”

5.
Based on your disclosure on pages 97 and 98, it appears that (i) you generate a significant amount of income from continuing operations before income taxes and
equity in net earnings of affiliated companies from locations outside of the United States, (ii) a significant portion of your provision (benefit) for income taxes is composed of non-U.S. amounts, and (iii) the difference between income
tax provision as calculated using the U.S. statutory rate and your effective tax rate is due, in part to adjustments related to foreign income. Please tell us what countries comprise a material amount of your foreign taxes and whether you generate a
disproportionate amount of taxable income in countries with very low tax rates.

 Cabot Response:

We reported a non-U.S. tax provision of $64 million for fiscal 2011. More than half of this provision related to three countries (Japan, China, and
Argentina) with the balance coming from twenty other countries, none of which had a material tax provision.

 We reported Foreign Income from
continuing operations of $228 million for fiscal 2011. We do not believe that a disproportionate amount was from countries with very low tax rates as less than 10% of this income was generated in countries with an effective tax rate of less than
10%. The effective tax rate on the remainder of the Foreign Income from continuing operations was 24%.

 Note T – Commitments and
Contingencies, page 101

 Contingencies – Environmental Matters, page 102

6.
We have reviewed the tables representing your estimated future undiscounted payments related to your respirator reserves you presented in your Forms 10-K for the
years ended September 30, 2010, 2009 and 2008. In 2008, you estimated those payments to be $1 million, $1 million and $2 million for the years ended September 30, 2009, 2010 and 2011. In 2009, you estimated those payments to be $1 million
and $2 million for the years ended September 30, 2010 and 2011. In 2010, you estimated those payments to be $4 million for the year ended September 30, 2011. We further note that you have made payments of $5 million, $2 million, $2 million
and $2 million for the four fiscal years ended September 30, 2011. In light of the fact that you have consistently paid more than what you had estimated for these payments, tell us your basis for your estimated future undiscounted payments as
reflected on page 48. Tell us why the $5 million payment in 2011 is not indicative of potential future payments.

Cabot Response:

 As discussed in
our 10-K, we have engaged, through counsel, Hamilton, Rabinovitz & Alshuler, Inc. (“HR&A”), a leading consulting firm in the field of tort liability valuation, to assist us in estimating future payments we will make for our
share of existing and future respirator liability claims. HR&A updated the reserve analysis and the estimate of future annual payments in 2010. At that time, we were aware of a potential settlement of a particular group of cases, which, by their
nature and jurisdiction, had unique characteristics. This settlement had not been contemplated in prior years. The increase in payments made in fiscal 2011 was principally the result of the settlement of these cases, which accelerated payments we
likely would have otherwise made in future years. We do not believe this calls into question the anticipated timing of our payments on our remaining claim population as such population is generally homogeneous and does not possess the unique
characteristics of the settled group.

 With respect to the seeming discrepancy between our estimated annual payments and our actual annual
payments, in our 10-K filings, we round the estimated payments and the actual costs incurred to the nearest million dollars. A comparison of our disclosed estimates for the last three fiscal years (including the revised estimate for fiscal 2011) and
our actual costs incurred is set forth in the table below and demonstrates that the HR&A estimates have been reasonably close to the actual amounts incurred, but because the numbers have been rounded, there appears to be a greater discrepancy:

 Year

Undiscounted
HR&A
Estimate

Actual
Payments

 2009

$
1.3 million

$
1.8 million

 2010

$
1.4 million

$
1.7 million

 2011

$
4.2 million

$
 5.0 million

 We continue to believe that we have enough visibility into our future cash flows to appropriately discount the liability.
We also provide the reader the reserve amount on both a discounted and an undiscounted basis so they understand the impact of the discounting.

Item 15 – Exhibits, Financial Statement Schedules, page 117

 Exhibit 10(a) – Credit Agreement dated August 26, 2011

7.
Please refer to comment 10 in our letter dated January 25, 2010. We note that you continue to omit the schedules and exhibits from the public filing of the new
credit agreement. Please file a complete copy of the credit agreement, including all schedules and exhibits, with your next Exchange Act report. In addition, please be advised that this agreement should have been filed as an exhibit to the Form 8-K
dated August 26, 2011 reporting the entry into this material definitive agreement. See Footnote (2) to Exhibit Table of Item 601 of Regulation S-K, which states that a Form 8–K exhibit is required only if relevant to the subject
matter reported on the Form 8–K report.

 Cabot Response:

We will file a complete copy of our credit agreement, including all schedules and exhibits, with our Quarterly Report on Form 10-Q for our fiscal quarter
ended March 31, 2012.

 With

February 15, 2012
 Via E-mail

Mr. Eduardo Cordeiro Executive Vice President and Chief Financial Officer Cabot Corporation Two Seaport Lane, Suite 1300 Boston, MA  02210
RE: Cabot Corporation
Form 10-K for the Year ended September 30, 2011
Filed November 29, 2011 Form 10-Q for the Quarter ended December 31, 2011
Filed February 8, 2012
  File No. 1-5667

Dear Mr. Cordeiro:
 We have reviewed your filings and have the following comments.  In some of our
comments, we may ask you to provide us with  information so we may better understand your
disclosure.
 Please respond to this letter within te n business days by providing the requested
information or by advising us when you will provide the requested response.  If you do not believe our comments apply to your facts and circum stances, please tell us w hy in your response.

After reviewing the information you provide in response to these comments, we may
have additional comments.               Form 10-K for the Year Ended September 30, 2011

 Item 7 – Management’s Discussion and Analys is of Financial Condition and Results of
Operations, page 30
 Results of Operations, page 37

1. You present total segment EBIT on page 42.  Since total segment EBIT represents a non-
GAAP measure when it is presen ted or discussed outside of your SFAS 131 footnote, in
future filings you should ensure either: (a) Total segment EBIT it is not presente d outside of your SFAS 131 footnote or
(b) If you choose to present total segment EBIT outside of your SFAS 131, you must
include all the disclosures required by Item  10(e) of Regulation S-K including the
following:

Mr. Eduardo Cordeiro Cabot Corporation February 15, 2012 Page 2

  reconcile from total segment EBIT to in come (loss) from continuing operations
before taxes and then on to net income to highlight the differences between the
non-GAAP measure and operating income,
 identify this amount as a non-GAAP performance measure,
 state the material limitations associat ed with use of the non-GAAP financial
measure as compared to the use of the most directly comparable GAAP financial
measure,
 state the manner in which management compensates for these limitations when
using the non-GAAP financial measure,
 explain why your management believes that this measure provides useful
information to investors,
 state how your management uses the non-GAAP measure,
 provide cautionary disclosure that th e non-GAAP measure presented may not be
comparable to similarly titled m easures used by other entities and
 state that this non-GAAP measure should not be considered as an alternative to
net income, which is determined in accordance with GAAP.
See also Question 104.04 of the SEC Complia nce and Disclosure Interpreta tions: Non-
GAAP Financial Measures.  Please show us  in your supplemental response what the
revisions will look like.
 Item 8 – Financial Statements and Supplementary Data, page 54

 Note A – Significant Acc ounting Policies, page 62

 General

2. Please disclose in future filings the types of e xpenses that you include in the cost of sales
line item and the types of expenses that you include in the selling and administrative
expenses line item.  Please also disclose  whether you include i nbound freight charges,
purchasing and receiving costs, inspection co sts, warehousing costs,  internal transfer
costs, and the other costs of your  distribution network in the co st of sales line item.  With
the exception of warehousing cost s, if you currently exclude a portion of these costs from
cost of sales, please disclose:
 in a footnote the line items that these ex cluded costs are included in and the amounts
included in each line item for each period presented, and
 in MD&A that your gross margins may not be  comparable to thos e of other entities,
since some entities include all of the costs re lated to their distribution network in cost
of sales and others like you exclude a porti on of them from gross margin, including
them instead in a line item such as selling and administrative expenses.
Please show us in your supplemental response what the revisions will look like.

Mr. Eduardo Cordeiro Cabot Corporation February 15, 2012 Page 3

 Inventories, page 62

3. You use both the average cost and FIFO methods to determine the cost of your
inventories for all non-U.S. inventories a nd certain U.S. inventories.  You should
generally use one inventory method for similar t ypes of inventories.  Please disclose in
future filings which types of inventory you use each method for, and disclose whether
you use both methods for any similar types of in ventory.  If so, pleas e also disclose your
basis for doing this.  Please show us in your  supplemental response what the revisions
will look like.
 Note S – Income Taxes, page 97

4. We note that you repatriated $24 million of high tax income in response to recent
changes in U.S. tax legislation.  Please tell us and revise your disclosure in future filings
to address how you concluded, in light of your  repatriation, that you have the ability and
intent to invest $887 million of undistributed earnings of non-U.S. subsidiaries indefinitely as of September 30, 2011.  Please refer to ASC 740-30-25-17 though 19.

5. Based on your disclosure on pages 97 and 98, it appears that (i) you ge nerate a significant
amount of income from continuing operations  before income taxes and equity in net
earnings of affiliated companies from locati ons outside of the United States, (ii) a
significant portion of your pr ovision (benefit) for income taxes is composed of non-U.S.
amounts, and (iii) the difference between inco me tax provision as calculated using the
U.S. statutory rate and your effective tax rate  is due, in part to adjustments related to
foreign income.  Please tell us what countries  comprise a material amount of your foreign
taxes and whether you generate a disproportiona te amount of taxable income in countries
with very low tax rates.
 Note T – Commitments and Contingencies, page 101

 Contingencies-Environmental Matters, page 102

6. We have reviewed the tables representing your estimated future undiscounted payments
related to your respirator re serves you presented in your Forms 10-K for the years ended
September 30, 2010, 2009 and 2008.  In 2008, you estimated those payments to be $1 million, $1 million and $2 million for the years ended September 30, 2009, 2010 and 2011.  In 2009, you estimated those payments to be $1 million and $2 million for the years ended September 30, 2010 and 2011.  In 2010, you estimated those payments to be $4 million for the year ended September 30, 2011.  We further note that you have made
payments of $5 million, $2 million, $2 million a nd $2 million for the four fiscal years
ended September 30, 2011.  In light of the fact that you have consistently paid more than
what you had estimated for these payments, te ll us you basis for your estimated future
undiscounted payments as reflected on page 48.  Tell us why the $5 million payment in 2011 is not indicative of potential future payments.

Mr. Eduardo Cordeiro Cabot Corporation February 15, 2012 Page 4

Item 15 – Exhibits, Financial Statement Schedules, page 117

 Exhibit 10(a) – Credit Agreement dated August 26, 2011

7. Please refer to comment 10 in our letter  dated January 25, 2010.  We note that you
continue to omit the schedules and exhibits  from the public filing of the new credit
agreement.  Please file a complete copy of the credit agreement, including all schedules
and exhibits, with your next Exchange Act report .  In addition, please be advised that this
agreement should have been filed as an e xhibit to the Form 8-K dated August 26, 2011
reporting the entry into this material defin itive agreement.  See Footnote (2) to Exhibit
Table of Item 601 of Regulation S-K, which st ates that a Form 8–K exhibit is required
only if relevant to the subject matter reported on the Form 8–K report.
 Form 10-Q for the Quarter Ended December 31, 2012

 General

8. Please address the above comments in your in terim filings as well, as applicable.

We urge all persons who are responsible for th e accuracy and adequacy of the disclosure
in the filing to be certain that the filing include s the information the Securities Exchange Act of
1934 and all applicable Exchange Act rules requir e.  Since the company and its management are
in possession of all facts relating to a company’s disclosure, they are responsible for the accuracy
and adequacy of the disclosures they have made.
 In responding to our comments, please provi de a written statement from the company
acknowledging that:
 the company is responsible for the adequacy an d accuracy of the disclo sure in the filing;

 staff comments or changes to disclosure in response to staff comments do not foreclose
the Commission from taking any action with respect to the filing; and

 the company may not assert staff comments as  a defense in any proceeding initiated by
the Commission or any person under the federa l securities laws of  the United States.

Mr. Eduardo Cordeiro Cabot Corporation February 15, 2012 Page 5

 You may contact Era Anagnosti, Staff Attorn ey, at (202) 551-3369 or, in her absence,
Pamela Long, Assistant Director, at (202) 551-3765 if you have any questions regarding legal or
disclosure matters.  Please contact Jeffrey Gor don, Staff Accountant, at (202) 551-3866 or, in his
absence, Jeanne Baker, Assistant Chief Acc ountant, at (202) 551-3691 if you have questions
regarding comments on the financial st atements and related matters.
      Sincerely,   /s/ Rufus Decker       Rufus Decker  Accounting Branch Chief

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-4631

       DIVISION OF
CORPORATION FINANCE

Mail Stop 4631
April 21, 2010
 Mr. Eduardo E. Cordeiro Executive Vice President and Chief Financial Officer Cabot Corporation Two Seaport Lane, Suite 1300 Boston, MA  02210
 RE: Form 10-K for the year ended September 30, 2009
  Form 10-Q for the peri od ended December 31, 2009
  Schedule 14A filed on January 28, 2010
  File No. 1-5667

Dear Mr. Cordeiro:
We have completed our review of your Fo rm 10-K and related filings and have no
further comments at this time.
If you have any further questions regardi ng our review of legal or disclosure
matters in your filings, please direct them to Era Anagnosti,  Staff Attorney, at (202) 551-
3369 or, in her absence, Craig Slivka, Special  Counsel, at (202) 551-3729.  Please contact
Jeffrey Gordon, Staff Accountan t, at (202) 551-3866 or, in his absence, Nudrat Salik,
Staff Accountant, at (202) 551-3692 if you have  questions regarding our review of the
financial statements and related matters.           S i n c e r e l y ,             R u f u s  D e c k e r          A c c o u n t i n g  B r a n c h  C h i e f

CORRESP
1
filename1.htm

Correspondence

 April 16, 2010

Rufus Decker, Accounting Branch Chief

 Division
of Corporation Finance

 United States Securities and Exchange Commission

100 F Street, N.E., Mail Stop 4631

 Washington,
D.C. 20549-4631

Re:
Cabot Corporation

 File
No. 001-05667

 Dear Mr. Decker:

This letter is being submitted in response to the Staff’s comment letter of March 17, 2010 in respect of Cabot Corporation’s Form 10-K for
the fiscal year ended September 30, 2009, Form 10-Q for the period ended December 31, 2009 and Definitive Proxy Statement on Schedule 14A filed on January 28, 2010. For ease of reference, we have restated the Staff’s comments
before our responses below.

 Form 10-Q for the Period Ended December 31, 2009

Note N – Foreign Currency Losses and Subsequent Events, page 26

1.
You disclose that you will be required to apply highly-inflationary accounting to your Venezuelan operations and that you anticipate this will result in a one-time
gain of less than $10 million during the second quarter of fiscal 2010. Please provide us with a comprehensive explanation of how you intend to account for the change in functional currency, including how you arrived at the estimated gain of $10
million. Please also address the impact of your accounting to any deferred tax assets and translation adjustments previously recorded related to these operations. Refer to ASC 830-10-45.

Cabot Response:

 Beginning
January 1, 2010 we will be required to apply highly-inflationary accounting to our 47.5% owned equity affiliate in Venezuela (the “equity affiliate”). This accounting treatment requires a change in the equity affiliate’s
functional currency from the local currency (Venezuelan Bolivar) to the parent’s reporting currency (USD). This highly-inflationary classification results from the fact that the cumulative inflation rate for the preceding 3 year period as of
January 1, 2010, exceeds 100 percent. When we change the functional currency, we will remeasure the entity’s financial statements as if the new functional currency (USD) were the reporting currency. Accordingly, effective January 1,
2010 all Bolivar denominated monetary

assets and liabilities will be considered foreign currency denominated assets and liabilities and will be remeasured to USD (the functional currency) with remeasurement adjustments in the period
recorded in the income statement. The USD will be the functional currency until the economic environment in Venezuela ceases to be considered highly-inflationary.

In accordance with ASC 830-10-45-10, the translated amounts for non-monetary assets and liabilities as of January 1, 2010 will become the accounting
basis in USD for those assets and liabilities in the period of change and subsequent periods. Regarding the Bolivar denominated monetary assets and liabilities as of January 1, 2010, the functional currency change from Bolivars to USD, in
isolation, has little or no financial statement impact as of that date. On a prospective basis, as prescribed by the accounting literature, foreign exchange movements on monetary assets and liabilities will be recorded directly to our statement of
operations.

 We are aware of the recent interim guidance announced by the SEC staff at the March 18, 2010 EITF meeting. The example in
the guidance focused on a situation where one rate was used to remeasure certain USD-denominated monetary balances and a different rate was used to translate the Bolivar balances into the USD reporting currency. As we have always used the official
exchange rate for remeasuring USD monetary assets and liabilities, as well as for translating from the Bolivar local currency financial statements to the USD reporting currency, the issue covered by the staff announcement is not applicable in our
particular facts and circumstances.

 A large portion of the deferred tax assets recorded prior to the highly-inflationary accounting related
to inflation indexing in the local Bolivar financial statements. In accordance with ASC 830-10-45-16, the deferred tax benefits attributable to any such indexing that occurs after the change in functional currency to the reporting currency shall be
recognized when realized on the tax return and not before. The deferred tax benefits that were recognized for indexing before the change in functional currency to the reporting currency will be eliminated when the related indexed amounts are
realized as deductions for tax purposes.

 As you are aware, on January 8, 2010, Venezuela announced a devaluation of its currency. This
event, coupled with the change in functional currency from the Bolivar to the USD gave rise to our subsequent event disclosure.

 At the time
of filing the Q1 2010 10-Q, we had prepared an itemized list of issues that could potentially result in a gain or loss to be recognized as a result of the devaluation, along with a range of the potential dollar value for each item. The items that
remained open and that we identified as having a potential P&L impact as of the date of the filing were as follows:

•

 Our equity affiliate, when considering only the monetary assets and liabilities denominated in Bolivars, excluding income taxes discussed below, had a
net monetary liability position. The impact of revaluing this net liability position from a pre-devaluation exchange rate of 2.15 to a post-devaluation exchange rate of 4.3 will result in an unrealized foreign exchange gain. Our 47.5% share of the
gain was estimated to be between $0 and $3 million based on our net monetary assets and liabilities denominated in Bolivars as of December 31, 2009.

 2

•

 There was a potential adjustment to the deferred tax liability held at the Cabot Corporation level based on the impact of the Bolivar’s
devaluation on our unremitted earnings pool. The estimated range of gain was between $0 and $4 million.

 Given the estimated
nature of these ranges and the preliminary nature of our review, we determined that it was most appropriate to provide a range of potential outcomes in our disclosure, and concluded upon the language presented in the 10-Q, presenting the potential
gain as less than $10 million.

 Subsequent to the filing of our Q1 2010 10-Q, we have determined that the gain as a result of the
re-measurement of the Bolivar net monetary liability position was $1 million. In addition, we have determined that the impact of the devaluation on Cabot’s share of unremitted earnings will reduce the deferred tax liability and result in a tax
benefit of approximately $2 million. Both of these items will be recorded in our Q2 2010 results and will be disclosed in the related footnotes.

Definitive Proxy Statement on Schedule 14A filed on January 28, 2010

Executive Compensation, page 22

Short-Term Incentive Compensation, page 26

Short-Term Incentive Compensation Payouts, page 29

2.
You disclose that 30% of the short-term incentive compensation is based on achievement of individual performance objectives; however, you do not disclose what these
individual objectives are, and how the compensation committee evaluated each named executive officer’s individual performance in reaching their respective individual goals. This is particularly important when no payouts were payable on the
basis of corporate performance. In accordance with Item 402(b)(2)(vii) of Regulation S-K, in future filings please describe the individual goals and performance objectives for each named executive officer. If a named executive officer’s
personal performance is measured against pre-established personal goals or individual objectives, please disclose the objectives and describe how performance or non-performance impacted the committee’s decision to award the personal objective
component of the short-term incentive compensation. Please note that to the extent that the committee’s decisions regarding a named executive officer’s individual performance were based upon a subjective evaluation, please ensure to
disclose each named executive officer’s personal objectives by also identifying the specific contributions made by each executive and contextualize those achievements for purposes of demonstrating how they resulted in specific compensation
decisions. Although quantitative targets for subjective or qualitative assessments may not be required, you should provide insight of how qualitative inputs are translated into objective pay determinations.

 3

 Cabot Response:

In future filings, we will include in this section of the Compensation Discussion and Analysis, to the extent material to our compensation decisions, a
discussion of the material elements considered by the Compensation Committee in awarding any short-term incentive compensation to a named executive officer on the basis of his individual performance. This discussion would include an assessment of
the named executive officer’s individual overall performance and/or specific achievements.

 In addition, in future filings, we expect the
discussion of the short-term incentive program would include substantially the following additional description of the individual performance portion of the bonus program:

“As explained above, 30% of an executive officer’s target bonus relates to individual job performance, and the
actual amount paid on this basis can range from 0% to 200% of that 30% target bonus. At the beginning of the fiscal year, the Compensation Committee, with input from the other independent directors, establishes the personal objectives for our CEO,
and each executive develops with the CEO his personal objectives for the year. In assessing each named executive officer’s individual performance, the Committee considers the officer’s personal achievements, including his achievements
against his personal objectives, as well as his individual contribution to the management team, leadership and management of his business or function.

The Committee does not assign specific numerical weightings or ratings to the individual goals and the performance of each
officer is evaluated as a whole. Furthermore, there are no formal threshold levels of achievement applicable to the individual performance component of the short-term incentive program. Ultimately, the determination of the payout of the portion of
the total bonus paid for individual performance is based on the subjective judgment of the Committee after reviewing all factors.”

 By
way of example, we expect the explanation of the basis upon which the Committee awards the individual performance portion of a bonus to include the following level of detail:

“. . . Mr. Prevost reviewed with the Committee his assessment of each named executive officer’s overall
performance for fiscal 2010. The Committee awarded [NEO] a bonus of $xxx,xxx based on his individual performance. The Committee identified the following significant accomplishments, which the Committee used as the basis for its compensation
decisions:

•

 [NEO] developed and implemented a restructuring plan in response to the unexpected and significant, global economic decline affecting the business,

•

 He oversaw the successful completion of the business’s capacity expansion in [region],

•

 He developed and implemented a comprehensive compliance strategy relating to
                    ,

•

 He developed and successfully led the implementation of organizational changes in the business to
                    ,

 4

•

 He was instrumental in the business achieving development milestones for the commercialization of new products,

•

 He was instrumental in the achievement of new customer development goals for the business.”

Long-Term Incentive Compensation Awards, page 30

3.
You state that the value of the stock option award “was based on the value of each officer’s targeted long-term incentive award for 2009”; however,
you do not disclose what that target value was. In future filings please discuss how the committee will determine the total value of the newly structured long-term incentive compensation (we note your discussion on page 27). For each named
executive, your disclosure should provide substantive analysis and insight into why the compensation committee determined that the levels of equity compensation were appropriate in light of the factors considered in deriving those payouts.

 Cabot Response:

In future filings, this section of the Compensation Discussion and Analysis will include more discussion of the factors the Compensation Committee
considered in determining the total value of long-term incentive awards made to the named executive officers. We expect the discussion would include substantially the following additional explanation of these factors.

“For each executive officer position within the Company, the Compensation Committee obtains from Pearl
Meyer & Partners, the Committee’s independent compensation consultant, information regarding current equity incentive compensation grant practices for comparable positions at companies in Cabot’s peer group and from compensation
survey reports. While the Committee uses this information to gain a general understanding of competitive market practices, actual award values are based on the Committee’s subjective analysis of a variety of factors. These factors include an
assessment of the individual’s position, role and responsibilities within the Company, the overall competitiveness of his total direct compensation, internal equity considerations based primarily on job responsibilities and experience, and
retention concerns. The Committee also considers the impact of the grants on equity incentive plan share usage, share dilution and the Company’s compensation expense. The awards made to the named executive officers are included in the tables
titled “Summary Compensation Table” and “Grant of Plan-Based Awards Table” below.”

 Grant of Plan-Based Awards
Table, page 36

4.
Please tell us how you are reporting the values in the “Threshold” column under the “Estimated Future Payouts Under Non-Equity Incentive Awards”
heading considering your disclosure in the third paragraph of your “Short-Term Incentive Compensation” discussion on page 26 where you state that if threshold performance is achieved, 50% of the target bonus opportunity is payable,
assuming that the threshold adjusted EBITDA is achieved. Please refer to Item 402(d)(2)(iii) of Regulation S-K.

 5

 Cabot Response:

As disclosed on page 26 of our proxy statement, actual short-term incentive compensation awards that are paid to an executive officer can range from 0%
to 200% of such officer’s target bonus opportunity, depending on the degree to which corporate (70% weighting) and individual performance (30% weighting) goals are achieved. Corporate performance was measured using two financial metrics:
(i) adjusted earnings before interest, taxes, depreciation and amortization (adjusted EBITDA) and (ii) net working capital (NWC) measured in days. For fiscal 2009, the adjusted EBITDA financial metric had a 65% weighting and the NWC
measured in days metric had a 35% weighting. As discussed in our proxy statement, if threshold performance for a corporate performance metric was achieved, 50% of the target bonus opportunity for that metric was payable. However, if the threshold
adjusted EBITDA goal was not achieved, none of the target bonus opportunity was payable on either of the corporate performance objectives. We do not establish formal threshold levels of achievement for individual performance.

We failed to meet the threshold performance for adjusted EBITDA for 2009 because of the decline we experienced in global demand for our products
following the significant decline in worldwide economic conditions that began in 2008. As a result, no payouts were payable on the basis of our corporate performance and we accordingly reported $0 in the “Grant of Plan-Based Awards Table”
for the threshold bonus amount payable for fiscal 2009 under our short-term incentive program as

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-4631

       DIVISION OF
CORPORATION FINANCE

Mail Stop 4631
March 17, 2010
 Mr. Eduardo E. Cordeiro Executive Vice President and Chief Financial Officer Cabot Corporation Two Seaport Lane, Suite 1300 Boston, MA  02210
 RE: Form 10-K for the year ended September 30, 2009
  Form 10-Q for the peri od ended December 31, 2009
  Schedule 14A filed on January 28, 2010
  File No. 1-5667

Dear Mr. Cordeiro:
We have reviewed your response letter  dated February 8, 2010 and have the
following additional comments.  If you disagree with a comment, we will consider your explanation as to why our comment is inappl icable or a revision is unnecessary.  Please
be as detailed as necessary in your explanat ion.  In some of our comments, we may ask
you to provide us with information so we may better understand your disclosure.  After
reviewing this information, we may or  may not raise additional comments.
  Please understand that the purpose of our re view process is to assist you in your
compliance with the applicable disclosure  requirements and to  enhance the overall
disclosure in your filing.  We look forward to  working with you in these respects.  We
welcome any questions you may have about our comments or on any other aspect of our review.  Feel free to call us at the telephone numbers listed at the end of this letter.

FORM 10-Q FOR THE PERIOD ENDED DECEMBER 31, 2009

Note N – Foreign Currency Losses and Subsequent Events, page 26

1. You disclose that you will be required to apply highly-inflationary accounting to
your Venezuelan operations and that you antic ipate this will result in a one time
gain of less than $10 million during the second quarter of fiscal 2010.  Please
provide us with a comprehensive explan ation of how you intend to account for the
change in functional currency, including how  you arrived at the estimated gain of
$10 million.  Please also address the imp act of your accounting to any deferred
tax assets and translation adjustments previously recorded related to these
operations.  Refer to ASC 830-10-45.

Mr. Eduardo E. Cordeiro
Cabot Corporation
March 17, 2010 Page 2 of 3
DEFINITIVE PROXY STATEMENT ON SCHEDULE 14A

FILED ON JANUARY 28, 2010

Executive Compensation, page 22

Short-Term Incentive Compensation, page 26
 Short-Term Incentive Compensation Payouts, page 29

2. You disclose that 30% of the short- term incentive compensation is based on
achievement of individual performance objectives; however, you do not disclose
what these individual objectives ar e, and how the compensation committee
evaluated each named executive officer’s individual performance in reaching their respective individual goa ls.  This is particularly important when no payouts were
payable on the basis of corporate perfo rmance.  In accordance with Item
402(b)(2)(vii) of Regulation S-K, in future  filings please desc ribe the individual
goals and performance objectives for each named executive officer.  If a named executive officer’s personal performance is measured against pre-established personal goals or individual objectives, pleas e disclose the objectives and describe
how performance or non-performance impacted the committee’s decision to award the personal objective compone nt of the short-term incentive
compensation.  Please note that to the extent that the committee’s decisions
regarding a named executive officer’s i ndividual performance were based upon a
subjective evaluation, please ensure to di sclose each named executive officer’s
personal objectives by also identifying the specific contributions made by each
executive and contextualize those achiev ements for purposes of demonstrating
how they resulted in specific compen sation decisions.  Although quantitative
targets for subjective or qualitative a ssessments may not be required, you should
provide insight of how qualitative inputs are transl ated into objective pay
determinations.

Long-Term Incentive Compensation Awards, page 30

 3. You state that the value of  the stock option award “was based on the value of each
officer’s targeted long-term incentive award for 2009”; however, you do not disclose what that target value was.  In future filings please discuss how the
committee will determine the total value of the newly structured long-term
incentive compensation (we note your discussion on page 27).  For each named executive, your disclosure should provide substantive analysis and insight into
why the compensation committee determin ed that the levels of equity
compensation were appropriate in light of the factors cons idered in deriving those
payouts.

Mr. Eduardo E. Cordeiro
Cabot Corporation March 17, 2010 Page 3 of 3    Grant of Plan-Based Awards Table, page 36

4. Please tell us how you are reporting the values in the “Threshold” column under
the “Estimated Future Payouts Under N on-Equity Incentive Awards” heading
considering your disclosure in the thir d paragraph of your “Short-Term Incentive
Compensation” discussion on page 26 where you state that if threshold performance is achieved, 50% of the target bonus opportunity is payable,
assuming that the threshold adjusted EB ITDA is achieved.  Please refer to Item
402(d)(2)(iii) of Regulation S-K.

*    *    *    *
 Please respond to these comments within  10 business days, or tell us when you
will provide us with a response.  Please provi de us with a response letter that keys your
responses to our comments and provides a ny requested information.  Detailed letters
greatly facilitate our review.  Please file your supplemental response on EDGAR as a correspondence file.  Please understand that we may have additional comments after reviewing your responses to our comments.
You may contact Era Anagnosti, Staff A ttorney, at (202) 551-3369 or, in her
absence, Craig Slivka, Special Counsel, at (202) 551-3729 if you have any questions
regarding legal or disclosure matters.  Pleas e contact Jeffrey Gordon, Staff Accountant, at
(202) 551-3866 or, in his absence, Nudrat Sa lik, Staff Accountant, at (202) 551-3692 if
you have questions regarding comments on the fi nancial statements and related matters.

 Sincerely,
 Rufus Decker
 Accounting Branch Chief

CORRESP
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Correspondence

 February 8, 2010

 Rufus Decker, Accounting Branch Chief

 Division of Corporation Finance

 United States Securities and Exchange Commission

 100 F Street, N.E., Mail Stop 4631

 Washington, D.C. 20549-4631

Re:

Cabot Corporation

File No. 001-05667

 Dear Mr. Decker:

 This letter is being submitted in response to the Staff’s comment letter of January 25, 2010 in respect of Cabot Corporation’s Form 10-K for the fiscal year ended September 30, 2009.
For ease of reference, we have restated the Staff’s comments before our responses below.

 Item 1 – Business, page 3

 Research and Development, page 11

1.
In future filings please include a cross-reference here to your discussion on page 39 regarding your Research and Technical Expenses.

Cabot Response:

 In future 10-K
filings, we will include a cross-reference to our discussion set forth in the Results of Operations section of the MD&A regarding our Research and Technical Expenses in substantially the following form:

 “Further discussion of our research and technical expenses incurred in each of the fiscal years ended September 30, 20XX, 20XX and
20XX appears in Management’s Discussion and Analysis of Financial Condition and Results of Operations in Item 7.”

 Legal Proceedings, page 21

 Environmental Proceedings, page 21

2.
We note your April 11, 2008 response to comment three of our letter dated March 28, 2008. We further note that at the end of the fourth paragraph you
continue to disclose that the claims relative to Cabot are without merit without explaining the basis of such belief. Please advise or otherwise in future filings comply with our prior comment three in full.

 Cabot Response:

 We acknowledge both
your comment and our previous response to the Staff. This was an oversight on our part. In future filings, if we include a discussion of the environmental-related lawsuits in Campana, Argentina, we confirm that we will delete language stating that
the claims relative to Cabot are without merit unless we include an explanation of the basis for our belief. We will continue to re-assess the materiality of these proceedings to determine whether a discussion of these proceedings in future filings
is necessary.

3.
In future filings please ensure your disclosure in this section complies with Item 103 of Regulation S-K, including disclosure about the name of the court or
agency in which a proceeding is pending, the date instituted, the parties thereto, a description of the factual basis alleged to underlie the proceeding and the relief sought. Please refer in particular to instruction 2 of Item 103 of
Regulation S-K.

 Cabot Response:

 In future filings we will ensure that our disclosure in this section complies with Item 103 of Regulation S-K, including disclosure about the name of the court or agency in which a proceeding is
pending, the date instituted, the parties thereto, a description of the factual basis alleged to underlie the proceeding and the relief sought.

 Respirator Liabilities, page 22

4.
We note your proposed disclosure in response to comment four of our letter dated March 28, 2008. We are unable to locate disclosure regarding your total cash
payments with respect to the Aearo-related liabilities, as indicated at the end of your proposed disclosure. Please advise, or otherwise, in future filings ensure that your revised disclosure is responsive to our prior comment.

 Cabot Response:

 We acknowledge our previous response to the Staff related to this matter. However, based upon our understanding of the requirements of Item 103 of Regulation S-K, we concluded that disclosure of cash
payments made by the Company in connection with respirator claims was more appropriate within Note T - Commitments and Contingencies. Accordingly, Note T - Commitments and Contingencies, of our 10-K, on page 98, contains the following disclosure

 2

regarding our annual cash payments for respirator claims: “Cash payments were $2 million, $2 million and $1 million during fiscal 2009, 2008 and 2007, respectively, related to this
liability.” This disclosure also includes a discussion of the Aearo payment arrangement. Nonetheless, in future filings, we will include disclosure regarding our annual cash payments with respect to respirator claims in both the Commitments and
Contingencies note to our consolidated financial statements and in the description of this matter in the legal proceedings section of our 10-K filings, to the extent such information continues to be appropriate.

 Item 7 – Management’s Discussion and Analysis of Financial Condition and Results of Operations, page 29

 Critical Accounting Policies, page 29

 Goodwill and Other Intangible Assets and Valuation of Long-Lived Assets, page 31

5.
In the interest of providing readers with a better insight into management’s judgments in accounting for goodwill, please disclose the following in future
filings:

•

 The reporting unit level at which you test goodwill for impairment and your basis for that determination;

•

 How you weight each of the methods used to value goodwill, including the basis for that weighting;

•

 How the methodologies used for valuing goodwill in the current year have changed since the prior year; and

•

 To the extent that any of your reporting units have estimated fair values that are not substantially in excess of the carrying value and to
the extent that goodwill for these reporting units, in the aggregate or individually, if impaired, could materially impact your operating results, please provide the following disclosures for each of these reporting units in future filings:

a.
Identify the reporting unit;

b.
The percentage by which fair value exceeds the carrying value as of the most recent step one test;

c.
The amount of goodwill;

d.
A description of the assumptions that drive the estimated fair value;

e.
A discussion of the uncertainty associated with the key assumptions. For example, to the extent that you have included assumptions in your discounted cash flow model
that materially deviates from your historical results, please include a discussion of these assumptions; and

f.
A discussion of any potential events and/or circumstances that could have a negative effect to the estimated fair value.

 If you have determined that the estimated fair value substantially exceeds the carrying value for all of your reporting units, please
disclose this determination. Please also provide the above disclosures, as applicable, for any long-lived assets or asset groups for which you have determined that undiscounted cash flows is not substantially in excess of the carrying value and to
the extent that the asset amounts, in the aggregate or individually, could materially impact your operating results or total shareholder’s equity. Please refer to Item 303 of Regulation S-K and Sections 216 and 501.14 of the SEC’s
Codification of Financial Reporting Policies for guidance. Please show us in your supplemental response what the revisions will look like.

 3

 Cabot Response:

 In response to your request, in future filings the Company will enhance its disclosures regarding the results of its latest annual goodwill impairment test as well as provide greater discussion of the
judgments and considerations made by management in performing the impairment tests relating to both goodwill and other long-lived assets. In addition, to the extent the Company has a situation where long-lived assets or reporting units have
estimated fair values that are not substantially in excess of the carrying value, and the potential impairment could materially impact our operating results, we will disclose additional information regarding the long-lived assets or reporting
unit(s) affected substantially in accordance with the information identified in your comment above.

 We intend to include in our 10-Q for the
quarter ended December 31, 2009 our enhanced disclosure relating to this matter, substantially as follows:

 “Goodwill and Long-Lived Assets

 Goodwill is comprised of the cost of business acquisitions in excess of
the fair value assigned to the net tangible and identifiable intangible assets acquired. Goodwill is not amortized but is reviewed for impairment annually, or when events or changes in the business environment indicate that the carrying value of the
reporting unit may exceed its fair value. The annual review is performed as of the period ending March 31 of each year.

 For the reporting units that carry goodwill balances, our impairment test consists of a comparison of each reporting unit’s carrying value to its estimated fair value. A reporting unit, for the purpose of the impairment test, is at or
one level below the operating segment level. The operating segment is presented in accordance with the FASB’s authoritative guidance on segment disclosures. We have five reporting segments, and six reporting units for the impairment review. Our
six reporting units are Rubber Blacks, Performance Products, Supermetals, Fumed Metal Oxides, Specialty Fluids, and New Business. The estimated fair value of a reporting unit is primarily based on discounted estimated future cash flows, and
secondarily we validate this model by considering other factors such as the fair value of comparable companies to our reporting units, and a reconciliation of the fair value of all our reporting units to our overall market capitalization. The
assumptions used to estimate the discounted cash flows are based on our best estimates about selling prices, production and sales volumes, costs, future growth rates, capital expenditures and market conditions over an estimate of the remaining
operating period at the reporting unit level. The discount rate is based on the weighted average cost of capital that is determined by evaluating the risk free rate of return, cost of debt, and expected equity premiums. If an impairment exists, a
loss is recorded to write-

 4

down the value of goodwill to its implied fair value. Our goodwill impairment testing methodologies have not changed since the prior year’s test. As a result of the test completed for
March 31, 2009, the estimated fair value substantially exceeded the carrying value of our reporting units.

 As of
December 31, 2009, our goodwill balance is allocated between two reporting units: Rubber Blacks, $XX million, and Fumed Metal Oxides, $XX million. There have been no goodwill impairment charges during the periods presented in these financial
statements.

 Our long-lived assets primarily include property, plant, equipment, long-term investments and assets held for
rent. We review the carrying values of long-lived assets for impairment whenever events or changes in business circumstances indicate that the carrying amount of an asset may not be recoverable. Such circumstances would include, but are not limited
to, a significant decrease in the market price of the long-lived asset, a significant adverse change in the way the asset is being used, a decline in the physical condition of the asset or a history of operating or cash flow losses associated with
the use of the asset.

 To test for impairment of assets we generally use a probability-weighted estimate of the future
undiscounted net cash flows of the assets or asset grouping over the remaining life of the asset to determine if the asset is recoverable. If we determine that the asset is not recoverable, we determine if there is a potential impairment loss by
calculating the fair value of the asset using a probability-weighted discounted estimate of future cash flows. The discount rate is based on the weighted average cost of capital that is determined by evaluating the risk free rate of return, cost of
debt, and expected equity premiums. To the extent the carrying value exceeds the fair value of the asset or asset group, an impairment loss is recognized in the statement of operations in that period. During the first quarter of fiscal 2010, a $X
million charge relating to the impairment of long-lived assets was recognized in the consolidated statement of operations.”

 Cash
Flows and Liquidity, page 46

6.
We note your credit facility agreement, which expires on August 3, 2010, contains various affirmative, negative and financial covenants, among other
restrictions. We further note that you intend to replace the credit facility when it expires. In future filings, please ensure that you clearly disclose the specific terms of any material debt covenants and whether you were in compliance with the
covenants as of the reporting date. In addition, if it is reasonably likely that you will not be in compliance with any of your material debt covenants, please disclose the required ratios/amounts as well as the actual ratios/amounts as of each
reporting date. This will allow readers to understand how much cushion there is between the required ratios/amounts and the actual ratios/amounts. Please also consider showing the specific computations used to arrive at the actual ratios/amounts
with corresponding reconciliations to US GAAP amounts, if necessary. See Sections I.D and IV.C of the SEC Interpretative Release NO. 33-8350. Please show us in your supplemental response what the revisions will look like.

 5

 Cabot Response:

 There are two material financial covenants in our revolving credit facility, subsidiary debt to total capitalization and total debt to total capitalization, that limit the additional debt we may incur.
The credit facility also contains an interest coverage covenant that becomes applicable only if Cabot’s credit rating is downgraded.

 For
the material covenants, we have a considerable cushion between the covenant limits and our actual ratios. In the past three years, the closest we have come to the subsidiary debt to total capitalization covenant limit was an actual percentage of 17%
versus a limit of 25%. For the same three year period, the closest we have come to the total debt to total capitalization covenant was an actual percentage of 39% versus a limit of 60%. Additionally, we continually monitor the risk that Cabot’s
credit rating may be downgraded by staying in regular contact with the rating agencies and monitoring our forecasted results. Our credit rating has been at BBB+/Baa1 for over 20 years and we are comfortable that the interest coverage covenant is not
at risk of being applied.

 In future filings, beginning with our 10-Q for the quarter ended December 31, 2009, we will disclose the
specific terms of our material debt covenants. The description of the material covenants in our current revolving credit facility will be as follows:

 “The credit facility contains various affirmative, negative and financial covenants which are customary for financings of this type, including limitations on our total debt to total capitalization
ratio and our total amount of subsidiary debt to total capitalization. The credit facility also contains an interest coverage covenant that becomes applicable only if Cabot’s credit rating is downgraded. As of XX, we were in compliance with all
of the covenants.”

 Additionally, if in the future it is reasonably likely that we will not be in compliance with any of our material
debt covenants, we will disclose in future filings the limits and actual amounts of these covenants along with any other required disclosures.

 Note S – Income Taxes

7.
Given your disclosure on page 92 that you have recognized losses from continuing operations in the U.S. for each of the three years ended September 30, 2009,
please enhance your disclosure in future filings to discuss the nature of the U.S deferred assets which have not been offset by valuation allowances and how you determined that these would be realized. In this regards, please address the following:

•

 Please expand your discussion of the nature of the positive and negative evidence that you considered, how that evidence was weighted , and
how that evidence 

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-4631

       DIVISION OF
CORPORATION FINANCE

Mail Stop 4631
January 25, 2010
 Mr. Eduardo E. Cordeiro Executive Vice President and Chief Financial Officer Cabot Corporation Two Seaport Lane, Suite 1300 Boston, MA  02210
 RE: Form 10-K for the year ended September 30, 2009
  File No. 1-5667

Dear Mr. Cordeiro:
We have reviewed your filing and have the following comments.  If you disagree
with a comment, we will consider your explanation as to why our comment is inapplicable or a revision is unnecessary.  Pl ease be as detailed as necessary in your
explanation.  In some of our comments, we may ask you to provide us with information so we may better understand your disclosure.  After reviewing this information, we may
or may not raise additional comments.   Please understand that the purpose of our re view process is to assist you in your
compliance with the applicable disclosure  requirements and to  enhance the overall
disclosure in your filing.  We look forward to  working with you in these respects.  We
welcome any questions you may have about our comments or on any other aspect of our review.  Feel free to call us at the telephone numbers listed at the end of this letter.

FORM 10-K FOR THE YEAR ENDED SEPTEMBER 30, 2009

 Item 1 - Business, page 3

 Research and Development, page 11

1. In future filings please include a cross-re ference here to your discussion on page
39 regarding your Research and Technical Expenses.

Mr. Eduardo E. Cordeiro
Cabot Corporation
January 25, 2010 Page 2 of 6   Legal Proceedings, page 21

 Environmental Proceedings, page 21

2. We note your April 11, 2008 response to co mment three of our letter dated March
28, 2008.  We further note that at the end of  the fourth paragraph you continue to
disclose that the claims relative to Cabot are without merit without explaining the basis of such belief.  Please advise or ot herwise, in future filings comply with our
prior comment three in full.

3. In future filings please ensure your disclosure in this section complies with Item 103 of Regulation S-K, including disclosu re about the name of the court or
agency in which a proceeding is pending, the date instituted, the parties thereto,  a
description of the f actual basis alleged to underlie the proceeding and the relief
sought.  Please refer in partic ular to instruction 2 of It em 103 of Regulation S-K.
 Respirator Liabilities, page 22

4. We note your proposed disclosu re in response to comment four of our letter dated
March 28, 2008.  We are unable to locate disclosure regarding your total cash
payments with respect to the Aearo-related liabilities, as indicated at the end of
your proposed disclosure.  Please advise, or ot herwise, in future filings ensure that
your revised disclosure is responsive to our prior comment.
 Item 7 – Management’s Discussion and Analysis of Financial Condition and Results of
Operations, page 29
 Critical Accounting Policies, page 29

 Goodwill and Other Intangible Assets and Valuation of Long-Lived Assets, page 31

5. In the interest of providing readers w ith a better insight into management’s
judgments in accounting for goodwill, please disclose the following in future filings:
• The reporting unit level at which you test goodwill for impairment and your
basis for that determination;
• How you weight each of the methods used to value goodwill, including the
basis for that weighting;
• How the methodologies used for valui ng goodwill in the current year have
changed since the prior year; and
• To the extent that any of your reporting units have estimated fair values that
are not substantially in excess of the carrying value and to the extent that
goodwill for these reporting units, in th e aggregate or individually, if

Mr. Eduardo E. Cordeiro
Cabot Corporation
January 25, 2010 Page 3 of 6
impaired, could materially impact your operating results, please provide the
following disclosures for each of these reporting units in future filings:
• Identify the reporting unit;
• The percentage by which fair value exceeds the carrying value as of the
most-recent step-one test;
• The amount of goodwill;
• A description of the assumptions that drive the estimated fair value;
• A discussion of the uncertainty associ ated with the key assumptions.  For
example, to the extent that you have included assumptions in your
discounted cash flow model that materi ally deviates from your historical
results, please include a disc ussion of these assumptions; and
• A discussion of any potential events and/or circumstances that could have
a negative effect to the estimated fair value.
If you have determined that the estimated fair value substantially exceeds the carrying value for all of your reporting units, please disc lose this determination.
Please also provide the above disclosures, as ap plicable, for any long-lived assets
or asset groups for which you have dete rmined that undiscounted cash flows is
not substantially in excess of the carrying value and to the extent that the asset
amounts, in the aggregate or individua lly, could materially impact your operating
results or total shareholder’s equity.  Please refer to Item 303 of Regulation S-K and Sections 216 and 501.14 of the SEC’s Codification of Financial Reporting
Policies for guidance.  Please show us in your supplemental response what the revisions will look like.
 Cash Flows and Liquidity, page 46

6. We note your credit facility agreem ent, which expires on August 3, 2010,
contains various affirmative, negative and financial covenants, among other restrictions.  We further note that you in tend to replace the cred it facility when it
expires.  In future filings, please ensure  that you clearly disclose the specific
terms of any material debt covenants and whether you were in compliance with
the covenants as of the reporting date.  In addition, if it is reasonably likely that
you will not be in compliance with any of  your material debt covenants, please
disclose the required ratios/amounts as well as the actual ra tios/amounts as of
each reporting date.  This will allow readers to understand how much cushion there is between the requir ed ratios/amounts and the ac tual ratios/amounts.  Please
also consider showing the specific computations used to arrive at the actual
ratios/amounts with corresponding reconc iliations to US GAAP amounts, if
necessary.  See Sections I.D and IV.C of the SEC Interpretive Release No. 33-
8350.  Please show us in your supplemental response what the revisions will look like.

Mr. Eduardo E. Cordeiro
Cabot Corporation
January 25, 2010 Page 4 of 6   Item 8 – Financial Statements and Supplementary Data, page 53

 Note S – Income Taxes, page 92

7. Given your disclosure on page 92 th at you have recognized losses from
continuing operations in the U.S. for each  of the three years ended September 30,
2009, please enhance your disclosure in future  filings to discuss the nature of the
U.S. deferred tax assets which have not been offset by a valuation allowance and
how you determined that these would be re alized.  In this re gard, please address
the following:
• Please expand your discussion of the na ture of the positive and negative
evidence that you considered, how that evidence was weighted, and how that
evidence led you to determine it was not appropriate to r ecord a valuation
allowance on the remaining deferred income tax assets.  You should consider
discussing the significant estimates and assumptions used in your analysis.
Please discuss how you determined the amount of the valuation allowance to record;
• Please disclose the amount of pre-tax in come that you need to generate to
realize the deferred tax assets;
• Please include an explanation of the antic ipated future trends included in your
projections of future taxable income; and
• Please disclose that the deferred tax liabilities you are relying on in your
assessment of the realizability of your de ferred tax assets will reverse in the
same period and jurisdiction and are of the same character as the temporary
differences giving rise to th e deferred tax assets.
Please show us in your supplemental response what the revisions will look like.
 Note T – Commitments and Contingencies, page 96

 Contingencies, page 97

 Environmental Matters, page 97

8. Regarding the environmental matters wh ich you are a party t o, please confirm
there is not a reasonable possibility  that a loss exceeding amounts already
recognized may have been incurred and the amount of that additional loss is material.  If there is a reasonable possibil ity, please disclose in future filings the
estimated additional loss, or range of loss, or state that such an estimate cannot be
made as required by FASB ASC 450-20-50.  Refer to SAB Topic 5:Y as well.
Please show us in your supplemental response what the revisions will look like.

Mr. Eduardo E. Cordeiro
Cabot Corporation
January 25, 2010 Page 5 of 6   Respirator Liabilities, page 98

9. Please disclose the number of claims in connection with respiratory products at
each balance sheet date, the number of cl aims filed for each period presented, the
number of claims dismissed, settled, or otherwise resolved for each period, and
the average settlement amount and total costs per claim.  Also, please address
historical and expected tre nds in these amounts and thei r reasonably likely effects
on operating results and liquidity.  Re fer to Question 3 of SAB Topic 5:Y.
 Item 15.  Exhibits, Financial Statement Schedules

 10. We note that you have not filed the e xhibits and schedules to the Credit
Agreement dated August 3, 2005 (Exhibit 10(a)(i )).  Please advise.  Refer to Item
601(b)(10) of Regulation S-K.  Otherwise,  please file a complete copy of this
agreement with your next Exchange Act report.

*    *    *    *
 Please respond to these comments within  10 business days, or tell us when you
will provide us with a response.  Please provi de us with a response letter that keys your
responses to our comments and provides a ny requested information.  Detailed letters
greatly facilitate our review.  Please file your supplemental response on EDGAR as a correspondence file.  Please understand that we may have additional comments after reviewing your responses to our comments.
We urge all persons who are responsible for the accuracy and adequacy of the
disclosure in the filings reviewed by the staff to be certain that they have provided all information required under the Securities Ex change Act of 1934 and that they have
provided all information investors require fo r an informed decision.  Since the company
and its management are in possession of all f acts relating to a company’s disclosure, they
are responsible for the accuracy and adequacy  of the disclosures they have made.

In connection with responding to our comments, please provide, in writing, a
statement from the company acknowledging that:
• the company is responsible for the adequacy and accuracy of the disclosure in their filings;
• staff comments or changes to disclosure  in response to staff comments do not
foreclose the Commission from taking any action with respect to the filing; and
• the company may not assert staff comme nts as a defense in any proceeding
initiated by the Commission or any pers on under the federal s ecurities laws of
the United States.

Mr. Eduardo E. Cordeiro
Cabot Corporation January 25, 2010 Page 6 of 6     In addition, please be advi sed that the Division of En forcement has access to all
information you provide to the staff of the Divi sion of Corporation Fi nance in our review
of your filing or in response to our comments on your filing.
 You may contact Era Anagnosti, Staff A ttorney, at (202) 551-3369 or, in her
absence, Craig Slivka, Special Counsel, at (202) 551-3729 if you have any questions
regarding legal or disclosure matters.  Pleas e contact Jeffrey Gordon, Staff Accountant, at
(202) 551-3866 or, in his absence, Nudrat Sa lik, Staff Accountant, at (202) 551-3692 if
you have questions regarding comments on the fi nancial statements and related matters.

 Sincerely,
 Rufus Decker
 Accounting Branch Chief

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-7010

       DIVISION OF
CORPORATION FINANCE

Mail Stop 7010
April 15, 2008

Via U.S. mail and facsimile

Mr. Patrick M. Prevost Chief Executive Officer
Cabot Corporation
Two Seaport Lane, Suite 1300
Boston, MA  02210
 RE: Form 10-K for the fiscal year ended September 30, 2007
File No. 001-05667

Dear Mr. Prevost:
We have completed our review of your Fo rm 10-K and related filings and have no
further comments at this time.

You may contact Errol Sanderson, Financia l Analyst, at (202) 551-3746 or, in his
absence, Jennifer Hardy, Legal Branch Chief, at (202) 551-3767 if you have any
questions regarding legal matters.  If you ha ve any questions regarding comments on the
financial statements and related matters, please direct them to Lisa Haynes, Staff Accountant, at (202) 551-3424 or, in her ab sence, to the undersi gned at (202) 551-3769.

       S i n c e r e l y ,             R u f u s  D e c k e r         Accounting Branch Chief

CORRESP
1
filename1.htm

Correspondence

 April 11, 2008

 Rufus Decker, Accounting Branch Chief

 Division of Corporation Finance

 United States Securities and Exchange Commission

 100 F Street, N.E., Mail
Stop 7010

 Washington, D.C. 20549-7010

Re:
Cabot Corporation

 File No. 001-05667

 Dear Mr. Decker:

 This letter is being submitted in
response to the Staff’s comment letter of March 28, 2008 in respect of Cabot Corporation’s Form 10-K for the fiscal year ended September 30, 2007. For ease of reference, we have restated the Staff’s comments before our
responses below.

 General

1.
Where a comment below requests additional disclosures or other revisions to be made, please show us in your supplemental response what the revisions will look like. These
revisions should be included in your future filings, including your interim filings.

 Cabot Response:

 The following supplemental responses include disclosures that we propose to include in our next filing that requires such disclosures, starting with our Form 10-Q for the
quarter ended March 31, 2008, which we expect to file on or before May 12, 2008. Accordingly, we believe that our enhanced disclosures described in responses 2, 3, 4, 8 and 9 will first appear, at the latest, in our Form 10-K for the year
ended September 30, 2008 while those disclosures described in responses 5, 6 and 7 will first appear in our Form 10-Q for the quarter ended March 31, 2008. We would be happy to discuss any of our responses at your convenience.

 Business

 Sales and Customers, page 8

2.
Please identify the silicone and microelectronics customers who represent a material portion of the Metal Oxides business sales. Please also identify the four material capacitor
customers mentioned on page 9. We note from your risk factor disclosure that the loss of any one or more of these customers could materially affect your business.

 Cabot Response:

 As stated in our 10-K, the Company has a number of important customers. We understand
Item 101(c)(1)(vii) of Regulation S-K to require disclosure of the name of any customer and its relationship with us if aggregate sales to the customer by one or more segments equal 10 percent or more of our consolidated revenues and the loss
of such customer would have a material adverse effect on us and our subsidiaries taken as a whole. We understand this to mean that if sales to a customer do not meet the 10 percent threshold, even if the loss of that customer would be important to
the Company, identifying the customer by name is not required by this Item. Accordingly, in our 10-K, we named The Goodyear Tire and Rubber Company as a customer (see page 5 under “Sales and Customers”, page 15 under the risk factor
starting “We depend on a group of key customers….” and page 101 under “Note T. Concentration of Credit Risk”), as it was the only customer to which sales in fiscal year 2007 amounted to at least 10 percent of our
consolidated revenues. In future filings, we will continue to name customers to which sales meet the 10 percent threshold. In addition, in future filings we will remove the word “materially” from the risk factor disclosure concerning
dependence on a group of key customers, and state that the loss of any one or more of our important customers, or a reduction in volumes sold to them because of a work stoppage or other disruption, could adversely affect our results of operations
until such business is replaced or the disruption ends.

 Legal Proceedings

 Environmental Proceedings, page 20

3.
Please either delete the statement in the third full paragraph on page 21 that you believe the claims are without merit or explain why you think they are without merit.

 2

 Cabot Response:

 In future filings that include a discussion of the environmental-related lawsuits in Campana, Argentina, we will delete language stating that the claims relative to Cabot are without merit. In addition, in preparing future filings we will
re-assess the materiality of these proceedings to determine whether a discussion of these proceedings is necessary.

 Other Proceedings

 Respirator Liabilities, page 21

4.
Please disclose the amount by which your total costs and payments have exceeded the amount you received from Aearo.

 Cabot Response:

 In future filings, the discussion set forth
in the second full paragraph on page 22 of our 10-K concerning the relationship between payments we receive from Aearo and make in connection with respirator claims will read substantially as follows:

 “The subsidiary disposed of the business in July 1995 by transferring it to a newly-formed joint venture called Aearo Corporation (“Aearo”)
and retained an equity interest in Aearo. Cabot agreed to have the subsidiary retain certain liabilities allocable to respirators used prior to the 1995 transaction so long as Aearo pays Cabot an annual fee of $400,000. Aearo can discontinue payment
of the fee at any time, in which case it will assume the responsibility for and indemnify Cabot against the liabilities allocable to respirators manufactured and used prior to the 1995 transaction. We have no liability in connection with any
products manufactured by Aearo after 1995. In fiscal years 2007 and 2008, our total cash payments in connection with these liabilities were approximately $1 million and $x million, respectively. In August 2003, Cabot and its subsidiary sold all of
the subsidiary’s equity interest in Aearo for approximately $35 million. This sale did not alter the arrangements described above.”

 Management’s Discussion and Analysis of Financial Condition and Results of Operations

 Fiscal Year 2007 compared to Fiscal
Years 2006 and 2005 – By Business Segment, page 40

5.
 Your presentation of total segment operating profit before taxes (PBT) constitutes a non-GAAP measure when it appears outside of your segment footnote.
Please

 3

revise your filing to clearly identify total segment PBT as a non-GAAP measure and provide a statement disclosing the reasons why management believes that
the presentation of the non-GAAP financial measure provide useful information to investors regarding your results of operations. For additional guidance, refer to Item 10(e) of Regulation S-K and Question 21 of our Frequently Asked Questions
Regarding the Use of Non-GAAP Financial Measures, which was released on June 13, 2003.

 Cabot Response:

 In future filings, immediately preceding the existing first paragraph of our “By Business Segment” discussion we will provide
substantially the following language:

 “Cabot’s chief operating decision-maker uses total segment operating profit before taxes
(“PBT”) to measure Cabot’s consolidated operating results, and segment operating profit before taxes to assess segment performance and allocate resources. Segment PBT includes equity in net income of affiliated companies, royalties
paid by equity affiliates, minority interest and allocated corporate costs and excludes interest expense, foreign currency transaction gains and losses, interest income, dividend income, as well as certain items that have not been allocated to a
segment as they are significant and unusual or infrequent. Segment PBT is a non-GAAP financial measure and is not intended to replace income (loss) from continuing operations, the most directly comparable GAAP financial measure. We believe segment
PBT assists investors by allowing them to evaluate changes in the operating results of our portfolio of businesses before non-operating factors and before items that are unusual or infrequent that affect net income. Furthermore, disclosure of
segment PBT is required in our financial statements under FAS 131. A reconciliation of segment PBT to income (loss) from continuing operations is shown in Note U of the Notes of our Consolidated Financial Statements.”

6.
As a related matter, please revise your discussion on segment MD&A to address the business reasons for changes between periods in the certain items expense line item that you
present in your segment footnote and in the table on page 41.

 Cabot Response:

 In future filings, a table and related narrative similar to that shown below will be included in our discussion of “certain items.”

 4

 “Details of the certain items for fiscal years 2007, 2006 and 2005 are as follows:

Years Ended September 30

2007

2006

2005

(Dollars in millions, pre-tax)

 Legal reserves/ settlement

$
(12
)

$
 —

$
 —

 Restructuring initiatives

 North America

(8
)

—

—

 Global

(3
)

(10
)

—

 Altona, Australia

(1
)

(11
)

(14
)

 European and Zierbena

—

—

(2
)

 Acquisition of flame synthesis technology

(4
)

—

—

 Environmental reserves/ settlement

(6
)

—

—

 Gwalia settlement payment

—

(27
)

—

 Cost reduction initiatives

—

(3
)

(15
)

 Long-lived asset impairment charges

—

—

(121
)

 Goodwill impairment charges

—

—

(90
)

 Total certain items, pre-tax

$
(34
)

$
(51
)

$
(242
)

 The $17 million decrease in pre-tax charges related to certain items in 2007 from 2006 was driven by lower
restructuring expenditures ($9 million), particularly our global initiative and the closure of our carbon black facility in Australia, and the $27 million payment made to the Sons of Gwalia in 2006 that did not recur in 2007. These decreases in
expenditures were partially offset by increased charges of $12 million related to legal reserves/settlement and $6 million related to environmental reserves/settlement in 2007. The $191 million decrease in pre-tax charges related to certain items in
2006 from 2005 was primarily related to the impairment of goodwill and long-lived assets in 2005 that did not recur in 2006 ($211 million), partially offset by the $27 million payment to the Sons of Gwalia in 2006.”

 Consolidated Financial Statements

 Note Q –
Earnings Per Share, page 92

7.
Please revise your filing to clarify whether the basic EPS adjustment to reduce weighted-average common shares outstanding for contingently issuable shares (3 million shares for
each period presented) is intended to represent the effect of outstanding unvested restricted stock, vested restricted stock or both.

 Cabot Response:

 As required by SFAS 128, paragraph 10, “…(o)utstanding common shares that are contingently returnable
(that is, subject to recall) shall be treated in the same manner as contingently issuable shares.” The amounts that we show as “contingently issuable shares” in our Basic EPS table in Note Q represent shares that have been awarded to
employees that are not yet vested. In future filings we will modify our disclosure in footnote (1) to the table to read “(r)epresents outstanding unvested restricted stock issued under Cabot’s Equity Incentive Plans.”

 5

 Note S – Commitments and Contingencies, page 96

8.
Please disclose how you account for (a) step rent provisions and escalation clauses and (b) capital improvement funding and other lease concessions, which may be
present in your leases. In addition, paragraph 5.n. of SFAS 13, as amended by SFAS 29, discusses how lease payments that depend on an existing index or rate, such as the consumer price index or the prime interest rate, should be initially included
in your minimum lease payments. If, as we assume, each of these items is included in computing your minimum lease payments and the minimum lease payments are recognized on a straight-line basis over the minimum lease term, the note should so state.
If our assumption is incorrect, please tell us how you considered the provisions in SFAS 13 and FTB 88-1 in reaching the conclusions you did regarding your accounting treatment.

 Cabot Response:

 As disclosed on page 49 of our 10-K,
“(w)e have operating leases primarily comprised of leases for transportation vehicles, warehouse facilities, office space and machinery and equipment.” Our disclosure in Note S is consistent with this statement. We also disclose, on page
19 of our 10-K, the properties we utilize and specifically identify those that are leased. Certain of these leases do have the characteristics/terms that are contemplated by SFAS 13, paragraph 5n, SFAS 29 or FTB 88-1 and we confirm to you that, in
all instances, the provisions of the aforementioned standards have been followed. Specifically, each of these items is included in computing minimum lease payments and such minimum lease payments are recognized on a straight-line basis over the
minimum lease term. In future filings, the discussion under “Operating Lease Commitments” on page 96 of our 10-K will include the following clarification:

 “Escalation clauses, lease payments dependent on existing rates/indexes, and other lease concessions are included in our minimum lease payments and such lease payments are recognized on a straight-line basis over
the minimum lease term.”

9.
We note your disclosure on page 34 that you are partially self-insured for certain third party liability, workers’ compensation and employee health benefits in the United
States and Canada. Please revise your filing here and on page 34 to disclose the extent to which you have excess loss insurance. Your revised disclosures should quantify the thresholds at which the excess loss insurance coverage would take effect
for each risk (e.g. workers compensation, third party liability, etc.) and should identify the risks for which you have no excess loss coverage.

 6

 Cabot Response:

 In future filings, to the extent that the accounting for self insurance reserves is considered a critical accounting policy, our discussion of the accounting treatment will include substantially the following language:

 “We are partially self-insured for certain third party liability, workers’ compensation and employee medical benefits in the United States. The
third party and workers’ compensation liabilities are managed through a wholly-owned insurance captive and the related liabilities are included in the consolidated financial statements; the employee medical obligations are managed by a third
party provider and the related liabilities are included in the consolidated financial statements. To limit our potential liabilities for these risks, however, we purchase insurance from third parties that provides individual and aggregate stop loss
protection. The aggregate self-insured liability for combined workers’ compensation and third party liabilities in the United States in fiscal year 2008 is $5.6 million, and the retention for medical costs in the United States is at most
$150,000 per person per annum. We have accrued amounts equal to the actuarially determined future liabilities. We determine the actuarial assumptions in collaboration with third party actuaries, based on historical information along with certain
assumptions about future events. Changes in assumptions for such matters as legal actions, medical costs and changes in actual experience could cause these estimates to change and impact our earnings and cash flows.”

 In future filings, we will include substantially the following discussion in our Commitments and Contingencies Note:

 “Self Insurance and Retentions for Certain Contingencies. The Company is partially self-insured for certain third party liability,
workers’ compensation and employee medical benefits in the United States. The third party and workers’ compensation liabilities are managed through a wholly-owned insurance captive and the related liabilities are included in the
consolidated financial statements; the employee medical obligations are managed by a third party provider and the related liabilities are included in the consolidated financial statements. To limit our potential liabilities for these risks, however,
the Company purchases insurance from third parties that provides individual and aggregate stop loss protection. The aggregate self-insured liability in fiscal year 2008 for combined workers’ compensation and third party liabilities in the
United States is $5.6 million, and the retention for medical costs in the Unit

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-7010

       DIVISION OF
CORPORATION FINANCE

Mail Stop 7010
March 28, 2008
 Via U.S. mail and facsimile

 Mr. Patrick M. Prevost Chief Executive Officer Cabot Corporation
Two Seaport Lane, Suite 1300
Boston, MA  02210

 RE: Form 10-K for the fiscal year ended September 30, 2007
File No. 001-05667

Dear Mr. Prevost:    We have reviewed your filings and have the following comments.  If you disagree with a comment, we will consider your explanation as to why our comment is inapplicable or a revision is unnecessary.  Pl ease be as detailed as necessary in your
explanation.  In some of our comments, we may ask you to provide us with information so we may better understand your disclosure.  After reviewing this information, we may
or may not raise additional comments.   Please understand that the purpose of our re view process is to assist you in your
compliance with the applicable disclosure  requirements and to  enhance the overall
disclosure in your filing.  We look forward to  working with you in these respects.  We
welcome any questions you may have about our comments or on any other aspect of our review.  Feel free to call us at the telephone numbers listed at the end of this letter.

FORM 10-K FOR THE YEAR ENDED SEPTEMBER 30, 2007

General
1. Where a comment below requests additional disclosures or other revisions to be
made, please show us in your supplemental response what the revisions will look like.
These revisions should be included in your future filings, including your interim
filings.

Mr. Patrick M. Prevost
Cabot Corporation
March 28, 2008 Page 2    Business

Sales and Customers, page 8
2. Please identify the silicone and microelectr onics customers who represent a material
portion of the Metal Oxides business sales.  Please also identify the four material
capacitor customers mentioned on page 9.  We note from your risk factor disclosure
that the loss of any one or more of th ese customers could materially affect your
business.

Legal Proceedings
 Environmental Proceedings, page 20

3. Please either delete the statement in th e third full paragraph on page 21 that you
believe the claims are without merit or e xplain why you think they are without merit.
 Other Proceedings

 Respirator Liabilities, page 21

4. Please disclose the amount by which your tota l costs and payments have exceeded the
amount you received from Aearo.
 Management’s Discussion and Analysis of Fi nancial Condition and Results of Operations

Fiscal Year 2007 compared to Fiscal Year s 2006 and 2005 – By Business Segment, page
40
5. Your presentation of total segment operating profit before taxes (PBT) constitutes a
non-GAAP measure when it appears outside of your segment footnote.  Please revise
your filing to clearly identif y total segment PBT as a non-GAAP measure and provide
a statement disclosing the reasons why mana gement believes that the presentation of
the non-GAAP financial measure provide usef ul information to investors regarding
your results of operations.  For additional gui dance, refer to Item 10(e) of Regulation
S-K and Question 21 of our Frequently As ked Questions Regarding the Use of Non-
GAAP Financial Measures, which was released on June 13, 2003.
6. As a related matter, please revise your di scussion on segment MD &A to address the
business reasons for changes between periods  in the certain items expense line item
that you present in your segment fo otnote and in the table on page 41.

Mr. Patrick M. Prevost
Cabot Corporation
March 28, 2008 Page 3    Consolidated Financial Statements

Note Q – Earnings Per Share, page 92
7. Please revise your filing to clarify whether the basic EPS adjustment to reduce
weighted-average common shares outstandi ng for contingently issuable shares (3
million shares for each period presented) is  intended to represent the effect of
outstanding unvested restri cted stock, vested re stricted stock or both.
 Note S – Commitments and Contingencies, page 96

8. Please disclose how you account for (a) step  rent provisions and escalation clauses
and (b) capital improvement funding and other lease concessions, which may be
present in your leases.  In addition, pa ragraph 5.n. of SFAS 13, as amended by SFAS
29, discusses how lease payments that depend on  an existing index or rate, such as the
consumer price index or the prime interest  rate, should be initi ally included in your
minimum lease payments.  If, as we assume, each of these items is included in computing your minimum lease payments and the minimum lease payments are recognized on a straight-line basis over the minimum lease term, the note should so
state.  If our assumption is incorrect, pl ease tell us how you considered the provisions
in SFAS 13 and FTB 88-1 in reaching the conclusions you did regarding your
accounting treatment.
9. We note your disclosure on page 34 that you ar e partially self-insur ed for certain third
party liability, workers’ compensation and employee health benefits in the United
States and Canada.  Please revise your filing here and on page 34 to disclose the
extent to which you have excess loss insura nce.  Your revise d disclosures should
quantify the thresholds at which the excess lo ss insurance coverage would take effect
for each risk (e.g. workers compensation, third party liability, etc) and should identify
the risks for which you have no excess loss coverage.

*    *    *    *
      Please respond to these comments with in 10 business days, or tell us when you
will provide us with a response.  Please provi de us with a response letter that keys your
responses to our comments and provides a ny requested information.  Detailed letters
greatly facilitate our review.  Pleas e furnish your response on EDGAR as a
correspondence file.  Please understand that we may have additional comments after reviewing your responses to our comments.

Mr. Patrick M. Prevost
Cabot Corporation March 28, 2008 Page 4
We urge all persons who are responsible for the accuracy and adequacy of the
disclosure in the filings reviewed by the staff to be certain that they have provided all information investors require for an info rmed decision.  Since the company and its
management are in possession of all facts re lating to a company’s disclosure, they are
responsible for the accuracy and adequacy of the disclosures they have made.

 In connection with responding to our comments, please provide, in writing, a statement from the company acknowledging that:
• the company is responsible for the adequacy and accuracy of the disclosure in
their filings;
• staff comments or changes to disclosure  in response to staff comments do not
foreclose the Commission from taking any action with respect to the filing; and
• the company may not assert staff comme nts as a defense in any proceeding
initiated by the Commission or any pers on under the federal s ecurities laws of
the United States.

  In addition, please be advi sed that the Division of En forcement has access to all
information you provide to the staff of the Divi sion of Corporation Fi nance in our review
of your filing or in response to our comments on your filing.
  You may contact Errol Sanderson, Financia l Analyst, at (202) 551-3746 or, in his
absence, Jennifer Hardy, Legal Branch Chief, at (202) 551-3767 if you have any
questions regarding legal matters.  Please cont act Lisa Haynes, Staff Accountant, at (202)
551-3424 or, in her absence, the undersigned at (202) 551-3769 if you have questions
regarding comments on the financial st atements and related matters.
          S i n c e r e l y ,              R u f u s  D e c k e r          A c c o u n t i n g  B r a n c h  C h i e f