SecProbe.io

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