SecProbe.io

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 AXCELIS TECHNOLOGIES, INC.
 108 Cherry Hill Drive

 Beverly, Massachusetts 01915

 (978) 787-4000

 December 29, 2025

 VIA EDGAR

 U.S. Securities and Exchange Commission

 Division of Corporation Finance

 100 F Street, NE

 Washington, D.C. 20549

 RE:
 Axcelis Technologies, Inc . (the "Company")

 Registration Statement on Form S-4

 File No. 333-292008
 Request for Effectiveness

 Ladies and Gentlemen:

 Pursuant to Rule 461 under the Securities
Act of 1933, as amended, the Company hereby respectfully requests that the effective date of the Company's Registration Statement
on Form S-4 (File No. 333-292008), filed with the U.S. Securities and Exchange Commission (the "Commission") on
December 8, 2025, as amended on December 29, 2025, be accelerated by the Commission to 4:00 p.m. New York time on December 31, 2025,
or as soon as practicable thereafter.

 We request that we be notified of such effectiveness
by a telephone call to Maxim Mayer-Cesiano of Skadden, Arps, Slate, Meagher & Flom LLP at (212) 735-2297 with such effectiveness
to also be confirmed in writing to maxim.mayercesiano@skadden.com.

 Very truly yours,

 Axcelis Technologies, Inc.

 By:
 /s/ Eileen Evans

 Eileen Evans

 Executive Vice President, Human Resources and Legal, and General Counsel

 cc:
 Maxim Mayer-Cesiano

 Skadden, Arps, Slate, Meagher & Flom LLP

Mail Stop 3030

September 18, 2017
Via E -mail
Mary G. Puma
President and Chief Executive Officer
Axcelis Technologies,  Inc.
108 Cherry Hill Drive
Beverly, MA 01915

Re: Axcelis Technologies,  Inc.
Form 10 -K for Fiscal Year E nded December 31, 201 6
Filed  March 14, 2017
File No. 000-30941

Dear M s. Puma :

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,

 /s/ Russell Mancuso

Russell Mancuso
Branch Chief
Office of Electronics and Machinery

cc: Matthew C. Dallett , Esq.
Locke Lord LLP

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Lynnette C. Fallon
 Direct Dial:  978-787-4120
 Lynnette.fallon@axcelis.com

September 8, 2017

FILED BY EDGAR

United States Securities and Exchange Commission
 Mail Stop 3030

Washington, D.C.  20549
 Attn: Amanda Ravitz, Assistant Director, Office of Electronics and Machinery

Re:          Axcelis Technologies, Inc. Form 10-K for the fiscal year ended December 31, 2016;  Filed March 14, 2017 — No. 000-30941

Dear Sir or Madam:

This letter is in response to your comment letter to Mary G. Puma, President and Chief Executive Officer of Axcelis Technologies, Inc. (“Axcelis” or the “Company”) dated September 6, 2017, and signed by Tim Buchmiller for Amanda Ravitz, Assistant Director, Office of Electronics and Machinery (the “Comment Letter”).  The response contained herein is numbered to correspond to the number used in the Comment Letter.

Item 1. Business, page 2.

1.              In your future filings, disclose the name of any customer and its relationship, if any, with you or any of your subsidiaries if sales to the customer are made in an aggregate amount equal to 10 percent or more of your consolidated revenues and the loss of such customer would have a material adverse effect on you and your subsidiaries taken as a whole.

Response:

In our future filings, we will disclose the name of any customer and its relationship, if any, with Axcelis or any of our subsidiaries if sales to the customer are made in an aggregate amount equal to 10 percent or more of our consolidated revenues and the loss of such customer would have a material adverse effect on Axcelis and our subsidiaries taken as a whole.

If you have any questions or request additional information, please do not hesitate to contact the undersigned at 978-787-4120 or at Lynnette.fallon@axcelis.com

Very   truly yours,

/s/   Lynnette C. Fallon

Lynnette   C. Fallon

Executive   Vice President HR/Legal and General Counsel

Mary G. Puma, President and CEO, Axcelis
 Kevin J. Brewer, Executive Vice President and CFO, Axcelis

Mail Stop 3030

September 6 , 2017
Via E -mail
Mary G. Puma
President and Chief Executive Officer
Axcelis Technologies,  Inc.
108 Cherry Hill Drive
Beverly, MA 01915

Re: Axcelis Technologies,  Inc.
Form 10 -K for the fiscal year ended December 31, 201 6
Filed  March 14, 2017
File No. 000-30941

Dear M s. Puma :

We have reviewed your filing an d 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 our comment 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
comment appl ies to your facts and c ircumstances, please tell us why in your response.

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

Item 1.   Business, page 2

1. In your future filings, disclose the name of any customer and its relationship, if any, with
you or any of your subsidiaries if sales to the customer are made in an aggregate amount
equal to 10 percent or more of your consolidated revenues and the loss of such customer
would have a material adverse effect on you and your subsidiaries taken as a whol e.

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.

Mary G. Puma
Axcelis Technologies,  Inc.
September 6, 2017
Page 2

 Please contact Tim Buchmiller  at (202) 551 -3635 or Russ ell Mancuso , Legal Branch
Chief,  at (202) 551 -3617 with any questions.

Sincerely,

/s/ Tim Buchmiller  for

Amanda Ravitz
Assistant Director
Office of Electronics and Machinery

cc: Matthew C. Dallett , Esq.
Locke Lord LLP

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Axcelis Technologies, Inc.

108 Cherry Hill Drive

Beverly, MA 01915

April 12, 2017

VIA EDGAR

Securities and Exchange Commission

Division of Corporation Finance

100 F Street, N.E.

Washington, DC 20549

Attn:  Mr. Tim Buchmiller

Re:  Axcelis Technologies, Inc. Registration Statement on Form S-3 (File No. 333-217192)

Ladies and Gentlemen:

Pursuant to Rule 461 of the Securities Act of 1933, Axcelis Technologies, Inc. (the “Company”) requests the acceleration of the effectiveness of the Registration Statement on Form S-3 (File No. 333-217192) for Friday, April 14, 2017 at 4:00 p.m. (EST), or as soon as possible thereafter.

In connection with this request, the Company acknowledges that:

(i) should the Commission or the staff, acting pursuant to delegated authority, declare the filing effective, it does not foreclose the Commission from taking any action with respect to the filing;

(ii) the action of the Commission or the staff, acting pursuant to delegated authority, in declaring the filing effective, does not relieve the  Company from its full responsibility for the adequacy and accuracy of the disclosure in the filing; and

(iii) the Company may not assert staff comments and the declaration of effectiveness as a defense in any proceeding initiated by the Commission or any person under the federal securities laws of the United States.

If you have any question regarding the foregoing, please call Matthew C. Dallett, Esq. of Locke Lord LLP at (617) 239-0303.

Very truly yours,

/s/ Lynnette C. Fallon

Lynnette C. Fallon

Executive Vice President, Human   Resources/Legal  and General Counsel

cc:                                Matthew C. Dallett

Locke Lord LLP

Mail Stop 3030
April 11 , 2017

Mary G. Puma
Chief Executive Officer
Axcelis Technologies, Inc.
108 Cherry Hill Drive
Beverly, Massachusetts 01915

Re: Axcelis Technologies, Inc.
  Registration Statement on Form S-3
Filed  April 7, 2017
  File No.  333-217192

Dear  Ms. Puma :

This is to advise you that we have not reviewed and will not review your registration
statement .

Please refer to Rules 460 and 461 regarding requests for acceleration.  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.

Please  contact Tim Buchmiller  at (202) 551 -3635  with any questions.

Sincerely,

/s/ Tim Buchmiller  for

Russell Mancuso
Branch Chief
Office of Electronics and Machinery

cc: Lynnette C. Fallon , Esq.
 General Counsel, Axcelis Technologies, Inc.

Matthew C. Dallett, Esq.
Locke Lord LLP

November 25, 2013

Via E -mail
Kevin J. Brewer
Executive Vice President and Chief Financial Officer
Axcelis Technologies, Inc.
108 Cherry Hill Drive
Beverly, MA 01915

 Re: Axcelis  Technologies, Inc.
Form 10 -K for the Fiscal Year Ended December 31, 2012
  Filed March 1, 2013
File No. 000-30941

Dear Mr. Brewer :

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 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/ Brian Cascio  for

        Martin James
        Senior Assistant Chief Accountant

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Axcelis Technologies, Inc.

108 Cherry Hill Drive

Beverly, MA 01915-1088

Direct Dial:  978-787-9551
 Fax:  978-787-4090

November 15, 2013

FILED BY EDGAR

United States Securities and Exchange Commission
 Mail Stop 6010

Washington, D.C.  20549
 Attn: Martin James, Senior Assistant Chief Accountant

Re:                             Axcelis Technologies, Inc. Form 10-K for the fiscal year ended December 31, 2012;  Filed March 1, 2013 — No. 000-30941

Dear Sir or Madam:

This letter is in response to your comment letter to Kevin J. Brewer, Executive Vice President and Chief Financial Officer of Axcelis Technologies, Inc. (“Axcelis” or the “Company”) dated November 1, 2013 signed by Martin James, Senior Assistant Chief Accountant (the “Comment Letter”).  The responses contained herein are numbered to correspond to the numbers used in the Comment Letter.

Form 10-K for the Fiscal year Ended December 31, 2012

Item 8. Financial Statements

Note 6. Inventories, net, page F-14

1.              Please describe how you assessed the recoverability of dry strip inventory as of December 31, 2012 for possible impairment.  Please also clarify how the assumptions inherent in that assessment changed during the six months ended June 30, 2013 which led to the $2.1 million impairment as described on page 9 of your Form 10-Q for the fiscal quarter ended June 30, 2013.

Response:

In response to the Staff’s comment, the Company advises the Staff that the Company’s assessment of the recoverability of dry strip inventory changed significantly based on new information obtained after the filing on March 1, 2013 of the Form 10-K for the fiscal year ended December 31, 2012 (the “Form 10-K”).

The determination of excess or obsolete inventory requires the Company to estimate the future demand for its products.  During the fourth quarter of 2012, the Company performed a comprehensive review and analysis of its worldwide inventory levels based on historic and projected inventory requirements for all of its products, components and parts. This analysis which was primarily driven by the Company’s internal projections and the factors discussed below was supported by industry outlook indicating that the semiconductor industry downturn would continue into 2013. As a result, the Company recorded a $13.4 million increase to inventory reserves in the fourth quarter of 2012.  This is disclosed in Note 6 of the 2012 financial statements included in the Form 10-K.

The Company’s inventory excess and obsolescence analysis as of December 31, 2012 took into account the December 2012 sale of certain intellectual property and other assets related to the Company’s dry strip product line to Lam Research Corporation which was also disclosed in the footnotes in the Form 10-K.  The contractual arrangement associated with the Lam sale provided for a 270 day transition period that extended into September 2013, during which the Company had the ability to accept purchase orders for the sale of 300 mm dry strip tools for a period of 180 days and these tools were required to ship within a further 90 days. In addition, the contract allowed the Company to sell certain 200 mm dry strip tools until December 2015 and to provide aftermarket support (spares, services, etc.) for the current installed base of both 300 mm and 200 mm systems in perpetuity.  The Company considered the impact of the Lam sale in its inventory excess and obsolescence analysis as of December 31, 2012.  At December 31, 2012, the recovery of $5.0 million of dry strip inventory was supported by forecasts to support aftermarket needs and an annual plan for 2013 that assumed the sale of 300 mm units during the transition period to key customers. Accordingly, the Company concluded that there was no reserve required for the 300 mm dry strip inventory as of December 31, 2012.

The charge recorded in the period ended December 31, 2012, as well as the Company’s expectations regarding the recoverability of the remaining dry strip inventory, were based on system bookings at the time of the filing of the Form 10-K on March 1, 2013 as well as the Company’s annual plan for 2013 and a three year strategic plan, which were developed using historical customer purchasing patterns, feedback from key customers, and industry data supporting projected capital spending.

After the filing of the Form 10-K and prior to the filing of the Company’s Form 10-Q for the three months ended March 31, 2013 (filed on May 6, 2013), the Company received new information from key 300 mm dry strip customers that indicated that certain 300 mm product sales that had been included in the annual plan would not occur within the contractual transition period.  This new information prompted the Company to review its 2013 annual plan inputs and, therefore, the salability of the 300 mm dry strip inventory.  The Company concluded that there

2

was not a high probability of new orders within the transition period and, accordingly, reconsidered the need for a reserve against the 300 mm dry strip inventory.  As a result, the Company recorded a $2.1 million charge, specific to the 300 mm product line, which represented the value of inventory no longer expected to be recoverable as of March 31, 2013. The remaining dry strip inventory of $2.9 million was projected to be recoverable through aftermarket support needs for the existing installed base of dry strip customers, and consists primarily of spare parts inventory to support these needs.  The Company included the following disclosure on page 9 of its Form 10-Q for the fiscal quarter ended March 31, 2013, “During the three months ended March 31, 2013, the Company recorded a charge to cost of sales of $2.1 million for 300mm dry strip components. Under the terms of the agreement with Lam, the Company was permitted to manufacture and sell dry strip products through September 2013. Due to changes in the forecasted sales of the Company’s dry strip products that become known in the current period, a portion of the dry strip inventory components were determined to be non-recoverable”.  A similar disclosure was included on page 9 of Form 10-Q for the fiscal quarter ended June 30, 2013.

The conclusion that a reserve for 300 mm dry strip inventory was not needed at December 31, 2012 was based on information available to the Company at that date through the filing date of the Form 10K. The Company’s conclusion that a reserve was required for a portion of the 300 mm dry strip inventory at March 31, 2013, was based on new information available subsequent to the filing of the Form 10-K on March 1, 2013 and prior to the filing of Form 10-Q for the period ended March 31, 2013 on May 6, 2013 and, therefore, the charge was recorded in the period ended March 31, 2013.

Note 13. Stock Award Plans and Stock Based Compensation, page F-18

2.              For stock options granted after July 1, 2012, the company started using the simplified method for estimating the expected life of options.  Previously the company used a forward looking lattice model.  Please respond to the following:

·                  Please tell us why the company switched from a forward looking lattice model to the simplified method for estimating the expected term for options granted after July 1, 2012. Refer to Question 6 of SAB Topic 14.

·                  Please tell us how the company applied FASB ASC 718-10-55-34 and Question 4 of SAB Topic 14 in determining the expected term of the options.

·                  Given that employee stock options do not typically vest until four years, please explain why the lower end of the range is below four years. Refer to Question 3 of SAB Topic 14.

3

Response

In response to the Staff’s comments the Company advises the Staff of the following:

·                  As indicated in Question 6 of SAB Topic 14 and related discussion, the use of the “simplified” method for “plain vanilla” options is allowed if a company concludes that due to significant changes to the terms of its option grants,  its historical share option exercise experience would no longer provide a reasonable basis upon which to estimate expected term. For grants subsequent to July 1, 2012, the life of the options was shortened from ten years to seven years with all other vesting provisions remaining consistent with earlier grants. As seven year options had not been offered by the Company before, the Company determined that the historical share option exercise experience would no longer be reliable and concluded that using the simplified method was appropriate until adequate history has been established for the seven year options. As more detailed historical information about exercise behavior for the seven year options becomes available over time, the Company expects that it will not continue to utilize the simplified method to estimate the expected term. Accordingly, the Company has used the simplified method to expense option award grants subsequent to July 1, 2012. The Company will continue to use the simplified method until sufficient historical data regarding exercise behavior for seven year awards is available.

·                  Both ASC 718-10-55-34 and Question 4 of SAB Topic 14 provide that an entity should aggregate individual awards into relatively homogenous groups for the purpose of determining expected term.  With respect to the 2012 Equity Incentive Plan adopted in May 2012, the Company has two groupings:  employees with a four year vesting period, and non-employee directors with a six month vesting period, as noted in Note 13(a), paragraph four in the Form 10-K.  The Company also considered treating employees and executives as separate groups. However, historical information indicated that exercise behavior was similar between these individuals. Therefore, the Company believes that only the employee and independent director groupings are relatively homogenous groups in terms of exercise and post-vesting employment termination behaviors for the purpose of determining expected term and that is consistent with the guidance in ASC 718-10-55-34 and Question 4 of SAB Topic 14.

·                  As noted in Question 3 of SAB Topic 14, a company cannot use an expected term that is less than the vesting period. As noted above, the Company currently has two groupings: employees with a four year vesting period, and non-employee directors with a six month vesting period. The lower end of the range in the disclosure on page F-19 in the Form 10-K (i.e., 3.8 years) relates to the non-employee directors’ options, with a six month vesting period.

4

As requested in the Comment Letter, the Company acknowledges that:

a.              the Company is responsible for the adequacy and accuracy of the disclosure in the filings discussed in the Comment Letter (the “filings”);

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

c.               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.

If you have any questions or request additional information, please do not hesitate to contact the undersigned at 978-787-9551

Very   truly yours,

/s/   Kevin J. Brewer

Kevin   J. Brewer

Executive   Vice President and Chief Financial Officer

Courtesy   copies:

Mary   G. Puma, Axcelis

5

November 1, 2013

Via E -mail
Kevin J. Brewer
Executive Vice President and Chief Financial Officer
Axcelis Technologies, Inc.
108 Cherry Hill Drive
Beverly, MA 01915

 Re: Axcelis  Technologies, Inc.
Form 10-K for the Fiscal Year E nded December 31, 2012
  Filed March 1, 2013
File No. 000-30941

Dear Mr. Brewer :

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 busines s days by providing the requested
information  or by advising us when you will provide the requested response.   If you do not
believe our comments appl y 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.

Form 10 -K for the Fiscal Year Ended December 31, 2012

Item 8.  Financ ial Statements

Note 6. Inventories, net, page F -14

1. Please describe how you assessed the recoverability of dry strip inventory as of
December 31, 2012 for possible impairment.  Please also clarify how the assumption s
inherent in that assessment changed during the six months ended June 30, 2013 which led
to the $2.1 million impairment as described on page 9 of your Form 10 -Q for the fiscal
quarter ended June 30, 2013.

Kevin J. Brewer
Axcelis Technologies, Inc.
November 1, 2013
Page 2

 Note 13.  Stock Award Plans and Stock Based C ompensation, page F -18

2. For stock options granted after July 1, 2012, the company started using the simplified
method for estimating the expected life of options.  Previously, the company used a
forward looking lattice model.  Please respond to the followi ng:

 Please tell us why the company switched from a forward looking lattice model to
the simplified method for estimating the expected term for options granted after
July 1, 2012.  Refer to Question 6 of SAB Topic 14.
 Please tell us how the company applied  FASB ASC 718 -10-55-34 and Question 4
of SAB Topic 14 in determining the expected term of the options.
 Given that employee stock options do not typically vest until four years, please
explain why the lower end of the range is below four years.  Refer to Qu estion 3
of SAB Topic 14.

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 rule s 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 Commission from taki ng 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 Kevin Kuhar, Accounta nt, at (202) 551 -3662 or Kate Tillan , Assistant
Chief Accountant , at (202) 551 -3604  if you have questions regarding comments on the financial
statements and related matters.   In this regard, do not hesitate to contact me at (202) 551 -3671
with any other questions.

        Sincerely,

        /s/ Kate Tillan for

        Martin James
        Senior Assistant Chief Accountant

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

         DIVISION OF
CORPORATION FINANCE
        August 9, 2010
 Mary G. Puma Chief Executive Officer Axcelis Technologies, Inc. 108 Cherry Hill Drive Beverly, Massachusetts 01915
Re: Axcelis Technologies, Inc.  Form 10-K for fiscal year ended December 31, 2009  Filed March 15, 2010  File No. 000-30941
 Dear Ms. Puma:
We have completed our review of your  Annual Report on Form 10-K and do not
have any further comments at this time.  If  you have any questions please contact Ruairi
Regan at (202) 551-3269 or Tim Buchmiller at (202) 551-3635.
Sincerely,    Russell Mancuso Branch Chief
cc: Lynnette C. Fallon (978) 787-4090

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Axcelis Technologies, Inc.

108 Cherry Hill Drive

Beverly, MA 01915-1088

Lynnette C. Fallon

Direct Dial:  978-787-4120

Fax: 978-787-4090

lynnette.fallon@axcelis.com

August 6, 2010

FILED BY
EDGAR

United States Securities and
Exchange Commission

Washington, D.C.  20549

Attn: Russell Mancuso,
Branch Chief

Re:                             Axcelis
Technologies, Inc. Form 10-K for the fiscal year ended December 31,
2009;  Filed March 15, 2010 —
No. 000-30941

Dear
Sir or Madam:

This letter is in response to your comment letter to Mary
G. Puma, Chief Executive Officer of Axcelis Technologies, Inc. (“Axcelis”
or the “Company”) dated July 30, 2010 signed by Russell Mancuso, Branch
Chief (the “Comment Letter”).  The
response contained herein is numbered to correspond to the number used in the
Comment Letter.

1.              Based
upon our review of the Part III information that you have incorporated by
references from your proxy statement into your Form 10-K, it does not
appear that you included any disclosure in response to Item 402(s) of
Regulation S-K in your proxy statement.
Please advise us of the basis for your conclusion that such disclosure
was not necessary and describe the process you undertook to reach that
conclusion.

Response:

In response to the Staff’s comment, the Company advises
the Staff that, prior to filing the Company’s Definitive Proxy Statement on
Schedule 14A, management (including representatives from human resources, legal
and finance departments and the Chief Executive Officer) considered the Company’s
compensation policies and practices for its employees to determine if these
policies and practices give rise to risks that are reasonably likely to have a
material adverse effect on the Company.
This assessment included (i) a review of the Company compensation
program’s policies and practices, (ii) identification of risks, if any,
related to the programs, (iii)  consideration of the materiality of  a potentially risk-related reward to the
total

compensation provided to the individual, and (iv) identification
of those aspects of the program and its oversight that provide risk
control.  Although all compensation
programs were considered, management’s review focused on the programs with
variability of payout and in which there is a potential for the participant to
directly affect payout.

Based on this review, management determined that the
compensation policies and practices for Axcelis’ employees do not create risks
that are reasonably likely to have a material adverse effect on the Company,
principally because:

(1) Base pay is a material component of all
employees’ total compensation package, so those employees who receive incentive
compensation have a total compensation package that is balanced; and

(2) Our incentive compensation programs are subject
to appropriate risk controls in their design and oversight:

·                  The
Company’s internal controls and risk management practices restrict risk-taking
that is not consistent with senior management’s determinations on appropriate
risk;

·                  Payment
of small bonuses for extraordinary effort or for achieving individual or team
goals are subject to approval by direct managers, and representatives of  human resources and finance departments, and,
for higher amounts,  a representative of
senior management;

·                  Payment
of sales commission plans are subject to calculation and approval by the  finance department and are tied to actual
receipt of payments from the customer;

·                  The
Company’s annual cash incentive plans have a balanced array of performance
measures established by the Compensation Committee of the Board of Directors
and which include both qualitative and quantitative assessments of performance;

·                  Achievement
of the objectives under the Company’s annual cash incentive plans is first
determined by senior management and the finance department and then approved by
the Compensation Committee of the Board of Directors prior to payment.

Accordingly, the Company concluded that no disclosure in
response to Item 402(s) of Regulation S-K was necessary.

As requested in the Comment Letter, the Company
acknowledges that:

a.              the
company is responsible for the adequacy and accuracy of the disclosure in the
filings discussed in the Comment Letter (the “filings”);

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

c.               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.

2

If you have any questions or request additional
information, please do not hesitate to contact the undersigned at 978-787-4120

  Very
  truly yours,

  /s/
  Lynnette C. Fallon

  Executive
  Vice President HR/Legal, General Counsel and Secretary

  Courtesy
  copies:

  Mary
  G. Puma, Axcelis

  Stephen
  G. Bassett, Axcelis

3

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

       DIVISION OF
CORPORATION FINANCE

Mail Stop 3030

 April 6, 2009
   VIA U.S. MAIL

 Mr. Stephen G. Bassett Axcelis Technologies, Inc. Executive Vice President and Chief Financial Officer 108 Cherry Hill Drive Beverly, MA 01915
 RE: Axcelis Technologies, Inc.
  Form 10-K for the fiscal year ended December 31, 2007
  Filed March 17, 2008   File No. 000-30941

Dear Mr. Bassett:

 We have completed our review of your Form  10-K and related filings and do not, at this
time, have any further comments.            S i n c e r e l y ,            B r i a n  C a s c i o         A c c o u n t i n g  B r a n c h  C h i e f

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Axcelis
Technologies, Inc.

108 Cherry Hill
Drive

Beverly, MA
01915-1088

Stephen
G. Bassett

Direct Dial:  978-787-4110

Fax: 978-787-4090

stephen.bassett@axcelis.com

March 20, 2009

FILED BY EDGAR

United States Securities and Exchange Commission

Mail Stop 6010

Washington, D.C.
20549

Attn: Brian Cascio, Accounting Branch Chief

Re:                               Axcelis
Technologies, Inc.

Form 10-K for the fiscal year ended December 31, 2007; Filed March 17,
2008

Form 10-Q’s for the quarterly periods ended March 31, 2008 and June 30,
2008

No. 000-30941

Dear Sir or Madam:

This
letter supplements our response to your comment letter to the undersigned
officer of Axcelis Technologies, Inc. (“Axcelis” or the “Company”) dated November 10,
2008 signed by Brian Cascio, Accounting Branch Chief (the “Comment Letter”).  The responses contained herein modify our
response in our letter to the Commission dated March 4, 2009 with respect
to the comment identified below, which is keyed to the heading contained in the
Comment Letter and is numbered to correspond to the number used in the Comment
Letter.

Form 10-K
for the fiscal year ended December 31, 2007

Form 10-K/A
Annual Report filed on September 29, 2008

6.     We note that the amended filing does not
contain the entire text of Item 15. Please amend your filing to include the
entire content of Item 15 of your annual report. Refer to Rule 12b-15 of
the Exchange Act.

Response:

As requested
by Mr. Cascio in our telephone conversation on March 19, 2009, we
hereby confirm that the Company did not intend to amend Item 8 of our Form 10-K
for the fiscal year ended December 31, 2007 when we filed the Form 10-K/A
on September 29, 2008.  The Form 10-K/A
was filed solely to

include
the financial statements of SEN Corporation, an SHI and Axcelis Company, in Item
15.  Accordingly, pursuant to our
discussion with Mr. Cascio, we will not file a further amendment to the
2007 Form 10-K that includes the entire content of Item 15.

Please
note that any significant subsequent events that would have been disclosed in the
notes to the FY2007 financial statements included in any new amendment to the
2007 Form 10-K, specifically Axcelis’ default on its debt obligations, the
pending sale of the investment in the Company’s joint venture and the estimated
impairment charges to be recognized in the fourth quarter of 2008, have already
been publicly disclosed in the Company’s Form 8-K and 12b-25 filings.

If
you have any questions or request additional information, please do not
hesitate to contact the undersigned at 978-787-4110

  Very truly yours,

  /s/ Stephen G. Bassett

  Stephen G. Bassett

  Executive Vice
  President and Chief Financial Officer

Courtesy copies:

Kristin Lochhead, SEC
Staff

Martin James, Senior Assistant Chief Accountant

Mary G. Puma, Axcelis

Lynnette C. Fallon, Axcelis

CORRESP
1
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Axcelis Technologies, Inc.

108 Cherry Hill Drive

Beverly, MA 01915-1088

Stephen
G. Bassett

Direct Dial:  978-787-4110

Fax: 978-787-4090

stephen.bassett@axcelis.com

March 4, 2009

FILED
BY EDGAR

United
States Securities and Exchange Commission

Mail Stop 6010

Washington,
D.C.  20549

Attn: Brian Cascio, Accounting Branch Chief

Re:                               Axcelis Technologies, Inc.

Form 10-K for the fiscal year ended December 31, 2007; Filed March 17,
2008

Form 10-Q’s for the quarterly periods ended March 31, 2008 and June 30,
2008

No. 000-30941

Dear
Sir or Madam:

This letter is in response to your
comment letter to the undersigned officer of Axcelis Technologies, Inc. (“Axcelis”
or the “company”) dated November 10, 2008 signed by Brian Cascio,
Accounting Branch Chief (the “Comment Letter”).
The responses contained herein are keyed to the headings contained in
the Comment Letter and are numbered to correspond to the numbers used in the
Comment Letter.

Form 10-K for the fiscal year ended December 31,
2007

Note 9. Other Assets

1.               Please tell us why
you have not classified the cost and amortization of products manufactured for
internal use as Property, Plant and Equipment.

Response:

Products manufactured for internal use are used for
customer demonstration purposes to support wordwide sales efforts, training and
research and development.

We have historically classified this investment as other
assets because a significant portion of these assets are utilized primarily for
customer demonstration and training which supports our worldwide sales
efforts.  We believe this classification
best represents the underlying nature of this investment, similar to deferred
charges.

We have also considered that these assets do not
necessarily represent permanent capital investments.  These assets may from time to time be
returned to inventory, refurbished and sold to customers as part of our normal
sales process.

The classification as other assets has no impact on our
results of operations because while the assets are in use, we recognize
amortization of these assets based upon their estimated useful lives (normally
5 years) and such amortization is included as a component of operating
expenses.  Also, classification does not
impact disclosures in the notes to the financial statements as we provide all
disclosures required for property, plant and equipment.

While
we acknowledge that classification as either property, plant and equipment or
other assets could be considered appropriate, as discussed above, we have
elected an accounting policy to classify these investments as other assets, and
we continue to believe this is appropriate.

Form 10-Q Quarterly Report as of March 31,
2008

Form 10-Q Quarterly Report as of June 30, 2008

Consolidated Balance Sheets, page 4

2.               Please tell us why
the investment in SEN increased significantly at March 31, 2008 and
decreased at June 30, 2008. Tell us where you have disclosed the reason
for these changes in the equity investment and related accounting treatment in
your filings.

Response:

The
increase in our investment in SEN as of March 31, 2008 resulted from a 12%
increase in the exchange rate of the Japanese Yen to US dollars during the first
quarter of 2008. The decrease in our investment in SEN as of June 30, 2008
resulted from a 6% decrease in the exchange rate of the Japanese Yen to US
dollars for the second quarter of 2008.
The underlying translation gain or loss is accounted for as a component
of other comprehensive income.  We
disclose in Item 7A: Quantitative and Qualitative Disclosures about Market Risk
in our Form 10K for 2007 that our investment in SEN is subject to foreign
currency exchange risks.  We will include
in our future filings additional commentary regarding the impact of foreign
currency fluctuations on the investment in SEN account.

Note
2 – Stock-based Compensation, page 7

3.               Please tell us
where you have provided the disclosures required paragraphs A240-241 of SFAS
123R.

Response:

We believe the disclosure relating to share-based
payments required in paragraphs A240-241 of SFAS 123R applies to annual
financial statements and not to financial statements for interim periods. Accordingly,
while we disclose total cost related to all share-based awards in our quarterly
financial statements, we omit other portions of the required annual disclosures.  We believe this abbreviated

interim disclosure is appropriate  and in accordance with paragraph 30 of APB 28 as
long as in the quarterly period there were no significant changes in the
estimates used in calculating this from those disclosed in the last annual
financial statements.

Item 2. Management’s Discussion and Analysis

Liquidity and Capital Resources, page 18

4.               Please revise
future filings to clarify how you plan to meet the redemption of your
convertible subordinated debt of $81 Million due on January 15, 2009.

Response:

Disclosure on the status of our convertible subordinated
debt was provided in our Form 10-Q for the quarter ended September 30,
2008 in Note 1 to the unaudited consolidated financial statements and in Item
2, Management’s Discussion and Analysis of Financial Condition and Results of
Operations in the Liquidity and Capital Resources section as well as in our Form 8-K
filed January 15, 2009.  We will
update this disclosure in our Form 10-K for the year ended December 31,
2008 and in all future filings through the period of repayment.

Form 10-Q/A Quarterly Report as of March 31,
2008

5.               We note that the
certifications required to be filed with the report are incomplete. These only
have the first 3 items. Please amend your filing to provide the appropriate
certifications. Refer to Item 601 of Regulation S-K.

Response:

Our certifications filed as exhibits to the Form 10-Q/A did
not include items 4 and 5 of paragraph (b)(31) of Item 601 of
Regulation S-K.  We understand that those items are not required to
be included in any amended report that does not include an amendment to
the Item 307 or 308 disclosures concerning disclosure controls and
procedures or internal control over financial reporting (Item 4 of Form 10-Q).  See,
e.g., the Division of Corporation Finance’s Compliance and Disclosure
Interpretations (Exchange Act Rules) Question 161.01, which formalized guidance
provided by Division staff over the last few years.  The Form 10-Q/A
did not contain an amendment to Item 4, so we omitted items 4 and 5 of the
certification.

Form 10-K/A Annual Report filed on September 29,
2008

6.               We note that the
amended filing does not contain the entire text of Item 15. Please amend your
filing to include the entire content of Item 15 of your annual report. Refer to
Rule 12b-15 of the Exchange Act.

Response:

We will file an additional Form 10-K/A to further amend
the filing so that it contains the entire text of Item 15.

As requested in the Comment
Letter, the company acknowledges that:

a.               the company is
responsible for the adequacy and accuracy of the disclosure in the filings
discussed in the Comment Letter (the “filings”);

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

c.               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.

If you have any questions or
request additional information, please do not hesitate to contact the
undersigned at 978-787-4110.

  Very
  truly yours,

  /s/
  Stephen G. Bassett

  Stephen
  G. Bassett

  Executive
  Vice President and Chief Financial Officer

Courtesy
copies:

Kristin
Lochhead, SEC Staff

Martin James, Senior Assistant Chief Accountant

Mary G. Puma, Axcelis

Lynnette C. Fallon, Axcelis

CORRESP
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Axcelis
Technologies, Inc.

108 Cherry Hill
Drive

Beverly, MA
01915-1088

Lynnette C. Fallon

Direct Dial:  978-787-4120

Fax:  978-787-4090

lynnette.fallon@axcelis.com

March 4,
2009

FILED BY EDGAR

United States Securities and Exchange Commission

Mail Stop 3030

Washington, D.C.
20549

Attn: Russell Mancuso, Branch Chief

Re:          Axcelis
Technologies, Inc.

Preliminary Proxy Statement on Schedule 14A

Filed February 20, 2009

File No. 000-30941

Dear Sir or Madam:

This
letter is in response to your comment letter to the undersigned officer of
Axcelis Technologies, Inc. (“Axcelis” or the “company”) dated February 26,
2009 signed by Russell Mancuso, Branch Chief (the “Comment Letter”).  For convenience, your comment is restated
below, followed by our response.

1.               We note that
comments remain outstanding regarding your annual report on Form 10-K for
the fiscal-year ended December 31, 2007 and related filings.  Please tell us whether you plan to print and
distribute your proxy statement and accompanying material to your shareholders
before you resolve those comments and, if so, tell us how you plan to
communicate any changes to your disclosure that occur between the time you
print your proxy statement and accompanying material and the time that the
comments are resolved.

Response:

We
have filed a letter with the Commission responding to the outstanding comments
regarding our annual report on Form 10-K for the fiscal-year ended December 31,
2007 (the “2007 10-K”) and related filings.
In that letter, we agreed to (i) include in future filings the
disclosure requested by the staff, to the extent required, and (ii) file a
10-K/A to amend the 2007 Form 10-K so that it contains the entire text of
Item 15 of Form 10-K, as required by Rule 12b-15 of the Exchange Act.  We believe that our response letter and

the 10-K/A, when filed,
will resolve the Commission’s outstanding comments.  After we file the 10-K/A, we will distribute
our proxy statement and accompanying materials to our shareholders.

As
requested in the Comment Letter, the company acknowledges that:

a.               the
company is responsible for the adequacy and accuracy of the disclosure in the
filing discussed in the Comment Letter (the “filing”);

b.              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

c.               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.

If
you have any questions or request additional information, please do not
hesitate to contact the undersigned at 978-787-4120.

  Very truly yours,

  /s/ Lynnette C. Fallon

  Lynnette C. Fallon

  Executive Vice
  President and General Counsel

Courtesy copies:

Geoffrey Kruczek, SEC
Staff

Mary G. Puma, Axcelis

Stephen G. Bassett,
Axcelis

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

       DIVISION OF
CORPORATION FINANCE
   M a i l  S t o p  3 0 3 0
       February 26, 2009

 Ms. Lynette Fallon Axcelis Technologies, Inc. Secretary and General Counsel 108 Cherry Hill Drive Beverly, MA  01915
Re: Axcelis Technologies, Inc.
Preliminary Proxy Statement on Schedule 14A Filed February 20, 2009
  File No. 000-30941

Dear Ms. Fallon:

We have limited our review of your filing to those issues we have addressed in
our comments.  Where indicated, we think you should revise your document in response
to these comments.  If you disagree, we w ill consider your explanation as to why our
comment is inapplicable or a revision is unneces sary.  Please be as detailed as necessary
in your explanation.  In some of our comme nts, we may ask you to provide us with
information so we may better understand your  disclosure.  After reviewing this
information, we may 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 any other aspect of our review.  Feel free to call us at the telephone numbers listed at the end of this letter.
 1. We note that comments remain outstanding regarding your annual report on Form
10-K for the fiscal-year ended December 31, 2007 and related filings.    Please tell
us whether you plan to print a nd distribute your proxy statement and
accompanying material to your shareholders before you resolve those comments and, if so, tell us how you plan to co mmunicate any changes to your disclosure
that occur between the time you prin t your proxy statement and accompanying
material and the time that the comments are resolved.

Lynette Fallon
Axcelis Technologies, Inc.
February 26, 2009 Page 2
*  *  *  *  *  *  *

As appropriate, please amend your filing and respond to these comments within
10 business days or tell us when you will provid e us with a response.  You may wish to
provide us with marked copies of the amendm ent to expedite our review.  Please furnish
a cover letter with your amendment that keys your responses to our comments and provides any requested information.  Detailed co ver letters greatly faci litate our review.
Please understand that we may have addi tional comments after reviewing your
amendment and responses to our comments.    We urge all persons who are responsi ble for the accuracy an d adequacy of the
disclosure in the filing to be certain that the filing includes all in formation required under
the Securities Exchange Act of 1934 and th at they have provided all information
investors require for an informed invest ment 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 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.

In addition, please be advise d that the Division of Enfo rcement 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 Geoffrey Kruczek at (202) 551-3641 or me at (202) 551-3617
with any questions.

    S i n c e r e l y ,

      Russell Mancuso     B r a n c h  C h i e f
 cc (via fax): Matthew C. Dallett—Edw ards, Angell, Palmer & Dodge LLP

Lynette Fallon
Axcelis Technologies, Inc. February 26, 2009 Page 3

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

       DIVISION OF
CORPORATION FINANCE

   Mail Stop 6010
November 10, 2008

VIA U.S. MAIL and FACSIMILE (978) 787-9027

 Ms. Stephen G. Bassett Axcelis Technologies, Inc.
Executive Vice President and Chief Financial Officer
108 Cherry Hill Drive Beverly, MA 01915
 RE: Axcelis Technologies, Inc.
  Form 10-K for the fiscal year ended December 31, 2007
  Filed March 17, 2008   File No. 000-30941

Dear Mr. Bassett:
 We have reviewed your filing and have the following comments.  We have
limited our review to only your financial stat ements and related disclosures and do not
intend to expand our review to  other portions of your docum ents.  Where indicated, we
think you should revise a filings in response to  these comments.  If you disagree, we will
consider your explanation as to why our comment is inapplicable or a revision is unnecessary.  Please be as deta iled as necessary in your expl anation.  In some of our
comments, we may ask you to provide us w ith information so we may better understand
your disclosure.  After reviewing this info rmation, we may 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 any other aspect of our review.  Feel free to call us at the telephone numbers listed at the end of this letter.

Mr. Stephen G. Bassett
Axcelis Technologies, Inc.
November 10, 2008
Page 2

Form 10-K Annual Report as of December 31, 2007

 Note 9.  Other Assets

1. Please tell us why you have not classified the cost and amortization of products manufactured for internal use as  Property, Plant and Equipment.
 Form 10-Q  Quarterly Report as of March 31, 2008

Form 10-Q  Quarterly Report as of June 30, 2008
 Consolidated Balance Sheets, page 4

2. Please tell us why the investment in SEN increased significantly at March 31,
2008 and decreased at June 30, 2008. Tell us  where you have disclosed the reason
for these changes in the equity investment  and the related accounting treatment in
your filings.
 Note 2 – Stock-based Compensation, page 7

3. Please tell us where you have provided th e disclosures required paragraphs A240-
241 of SFAS 123R.

Item 2.  Management’s discussion and Analysis
Liquidity and Capital Resources, page 18
4. Please revise future filings to clarify how  you plan to meet the redemption of your
convertible subordinated debt of  $81 Million due on January 15, 2009.

Form 10-Q/A  Quarterly Report as of March 31, 2008
5. We note that the certifications  required to be filed with the report are incomplete.
These only have the first 3 items. Pl ease amend your filing to provide the
appropriate certifications .   Refer to Item 601 of Regulation S-K.

Form 10-K/A Annual Report filed on September 29, 2008
6. We note that the amended filing does not c ontain the entire te xt of Item 15.
Please amend your fining to include the en tire content of It em 15 of your annual
report.  Refer to Rule 12b-15 of the Exchange Act.

*****

Mr. Stephen G. Bassett
Axcelis Technologies, Inc. November 10, 2008
Page 3
 As appropriate, please respond to these co mments within 10 business days or tell
us when you will provide us with a response.  Please furnish a cover letter with your
response that keys your responses to our  comments and provides any requested
information.  Detailed cover le tters greatly facilitate our re view.  Please understand that
we may have additional comments after re viewing your responses to our comments.
   We urge all persons who are responsi ble for the accuracy and adequacy of the
disclosure in the filing to be certain that the filing includes all in formation required under
the Securities Exchange Act of 1934 and th at they have provided all information
investors require for an informed decision.  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 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 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 comme nts as a defense in any proceeding
initiated by the Commission or any person under the federal secu rities laws of the
United States.

In addition, please be advise d that the Division of Enfo rcement 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 Jong Hwang at (202) 551-3327 if you have questions about
these comments.  In this regard, please do not hesitate to contact  me at (202) 551-3676
with any other questions.
 Sincerely,

Brian Cascio Accounting Branch Chief

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

       DIVISION OF
CORPORATION FINANCE

Mail Stop 6010

                October 17, 2007  Stephen G. Bassett Chief Financial Officer Axcelis Technologies, Inc.  108 Cherry Hill Drive Beverly, Massachusetts  01915
 RE: Axcelis Technologies, Inc.
  Form 10-K for the fiscal year ended December 31, 2006
  Filed March 15, 2007   File No.  000-30941

Dear Mr. Bassett:   We have completed our review of your Form  10-K and related filings and do not, at this
time, have any further comments.            S i n c e r e l y ,            M a r t i n  F .  J a m e s         Senior Assistant Chief Accountant

CORRESP
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BY EDGAR

October 10, 2007

Brian Cascio

Accounting Branch Chief

Division of Corporation Finance

Securities and Exchange
Commission

100 F Street, N.E.

Washington, DC 20549-6010

Re:          Axcelis Technologies, Inc.

Form 10-K for the fiscal year ended
December 31, 2006

Form 10-Q for the quarterly
period ended March 31, 2007

File No. 000-30941

Dear Mr. Cascio:

The following
responds to your letter of August 28, 2007 to the undersigned regarding the
Forms 10-K and 10-Q referred to above filed by Axcelis Technologies, Inc. (the “Company”).

For convenience, each of your comments is
restated below, followed by our response.

Form 10-K for the fiscal year ended December
31, 2006

Consolidated Statements of Operations, page
F-2

1.     We reference your response to
prior comment one in our letter dated July 20, 2007. We note that you do not
separately track costs in a format that would enable you to separately report
costs of systems, services and royalties. However, we see that services revenue
is approximately 40% of total revenue. Under Article 5-03(b) (1) and (2) of
Regulation S-X, you should separately state costs and expenses applicable to
each category of sales and revenues. To the extent that you are able to
estimate the costs applicable to each category of sales presented on the fact
of the income statement, future filings should be revised to reflect this
presentation.

2.     As a related matter, we
continue to believe that the gross profit for systems and services should be
separately discussed in the results of operations section of MD&A.

Historically, as previously disclosed in the
notes to the financial statements, service revenue included revenues from spare
parts, equipment upgrades and maintenance services, collectively, aftermarket
revenues. We believe this presentation of revenues was and continues to be meaningful
to the readers of our financial statements due to the cyclicality of system
sales and the fact that aftermarket revenues do not fluctuate as much as
systems revenues from industry cycle to cycle. However, in order to provide a
meaningful classification of costs of goods sold, we will reclassify the system
revenue components of amounts historically reported as service revenue. Under
this revised classification, system revenue will include revenue from systems
sales, sales of spare parts and product upgrades. Service revenue will include
revenue received from maintenance and service contracts and service hours
provided by on-site service personnel. This reclassification will allow us to
allocate direct and shared costs of product and service revenues in a
supportable and meaningful manner. As such, we will present in the statement of
operations separate amounts for costs of system and service revenues. Reclassification
of amounts reported in prior periods will be made to permit comparison. Such
reclassifications will not affect total revenues, total gross profit or net
income or loss, as previously reported. This reclassification will be disclosed
in the notes to our financial statements and we will update the accounting
policy with respect to revenue categories.

As mentioned above, we continue to believe
that the disclosure of total aftermarket revenues, including spare parts,
equipment upgrades and service is important and relevant information to the
users of our financial statements. Accordingly, in MD&A section of our
quarterly and annual filings, we will supplementally disclose the portion of
product revenue that relates to aftermarket activities.

The Company will separately discuss gross
profit for products and services in the results of operations section of
MD&A in future filings.

Please direct any questions or further
comments regarding this letter to me at the above address or contact me
directly by telephone at (978) 787-4110 or by email at Stephen.Bassett@axcelis.com.

  Sincerely,

2

  /s/ Stephen G. Bassett

  Stephen G. Bassett

  Executive Vice President and

  Chief Financial Officer

  cc:

  Kristin Lochhead

  Securities and Exchange Commission

3

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BY EDGAR

August 17, 2007

Brian Cascio

Accounting Branch Chief

Division of Corporation Finance

Securities and Exchange Commission

100 F Street, N.E.

Washington, DC 20549-6010

Re:                               Axcelis
Technologies, Inc.

Form 10-K for the fiscal year ended December 31, 2006

Form 10-Q for the quarterly period ended March 31, 2007

File No. 000-30941

Dear Mr. Cascio:

The following
responds to your letter of July 20, 2007, to the undersigned regarding the
Forms 10-K and 10-Q referred to above filed by Axcelis Technologies, Inc. (the “Company”).

For
convenience, each of your comments is restated below, followed by our response.

Form 10-K for the fiscal
year ended December 31, 2006

Consolidated Statements
of Operations, page F-2

1.                                       We
see that you separately disclose revenue generated from sales of systems,
services and royalties.  In future
filings, please revise your income statement to also separately disclose the
related costs of generating those revenues.
Refer to Article 5-03(b)(1) and (2) of Regulation S-X.  As a related matter, the gross profit for
systems, services and royalties should be separately discussed in the results
of operations section of MD&A.

The Company operates in one business segment, which is
the manufacture of capital equipment for the semiconductor manufacturing
industry. Our primary revenue driver is system sales. We view revenues from
spare parts, equipment upgrades and maintenance services as a derivative of
system sales and do not view these revenues as a separate business.
Accordingly, we built our financial systems consistent with this view and we do
not track these costs in a format that would enable us to report them
separately. For instance, certain shared costs of systems, services and
royalties such as variances, material scrap, training and valuation reserves
cannot be attributed to specific cost of revenue categories. Therefore, we have
no practical manner in which to allocate such costs in way that would provide
more meaningful financial information to our investors.

Consolidated Balance
Sheets, page F-3

2.                                       In
future filings, please revise to clearly label your long term debt as “convertible
subordinated debt,” as described in the footnotes to your financial statements.

We will provide
the requested disclosure in future filings.

Notes to
Consolidated Financial Statements

Note 2.  Significant Accounting Policies, page F-6

Revenue
Recognition, page F-8

3.                                       Please
tell us and revise future filings to clearly disclose your accounting policy
for recognizing revenue from royalty arrangements.  Please note that it should be evident from
your disclosure that the royalty revenue is from a related party.

The Company’s accounting policy for recognizing
revenue from royalty arrangements is as follows:

Royalty revenue is primarily earned under the terms of
our license agreement with SEN. Royalty revenue is recorded at the time SEN
notifies the Company that royalties have been earned.

We will describe this policy in future filings.

Form 10-Q for the
quarterly period ended March 31, 2007

Consolidated Statement of
Cash Flows, page 5

4.                                       We
see that you currently present the cash dividend from SEN within operating
activities in your consolidated statement of cash flows.  Please tell us why you should not record the
dividend as a component of net cash provided by investing activities.  We reference paragraph 16(b) of SFAS 95 which
states that returns of investment in equity instruments are generally recorded
as investing activities.

In 2006, the Company and
Sumitomo Heavy Industries agreed upon an annual dividend relating to SEN’s
fiscal year ended March 31, 2006. The two shareholders instructed SEN to
dividend 40% of SEN’s net earnings for that year. On January 31, 2007, the
Company received a payment of approximately $5.7 million representing its 50%
share of the dividend.

 2

Paragraph 16(b) of SFAS
95 states “returns of investment in equity instruments are generally recorded
as investing activities”.  In this
situation, the Company believes that the cash received from SEN represents a
return on investment, rather than return of investment. The
Company holds this position as the intent of the dividend payment was to
distribute a portion of SEN’s net earnings to the shareholders. Further
clarification is provided in Example 1 of Appendix C of Statement 95.  The example illustrates that a dividend
received from an affiliate, as well as undistributed earnings of an affiliate,
are classified as operating activities in the statement of cash flows.

Because the cash payment
received from SEN was a dividend payment and not a return of the company’s
original investment in the joint venture, the Company’s position is
classification of the cash receipt within operating activities is appropriate.

In connection
with this letter, as requested, the Company acknowledges that (i) the Company
is responsible for the adequacy and accuracy of the disclosure in the 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.

Please direct
any questions or further comments regarding this letter to me at the above
address or contact me directly by telephone at (978) 787 - 4110 or by email at
Stephen.Bassett@axcelis.com.

  Sincerely,

  /s/ STEPHEN G.
  BASSETT

  Stephen G. Bassett

  Executive Vice President and

  Chief Financial Officer

cc:                                 Kristin
Lochhead

Securities and Exchange Commission

 3

Mail Stop 6010

July 20, 2007

VIA U.S. MAIL and FACSIMILE

Stephen G. Bassett
Chief Financial Officer
Axcelis Technologies, Inc.
108 Cherry Hill Drive
Beverly, Massachusetts  01915

 RE: Axcelis Technologies, Inc.
  Form 10-K for the fiscal year ended December 31, 2006
  Filed March 15, 2007
  Form 10-Q for the quarterl y period ended March 31, 2007
  File No.  000-30941

Dear Mr. Bassett:

We have reviewed your filing and have the following comments.  We have
limited our review of your filing to those i ssues we have addressed in our comments.
Where indicated, we think you should revise  your document in response to these
comments.  If you disagree, 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
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 any other aspect of our review.  Feel free to call us at the telephone numbers listed at the end of this letter.

Mr. Bassett
Axcelis Technologies, Inc.
July 20, 2007 Page 2
Form 10-K for the fiscal year ended December 31, 2006

Consolidated Statements of Operations, page F-2
1. We see that you separately disclose reve nue generated from sales of systems,
services and royalties. In future filings , please revise your income statement to
also separately disclose the related cost s of generating those revenues.  Refer to
Article 5-03(b)(1) and (2) of Regulation S-X.  As a related matter, the gross profit
for systems, services and royalties should be  separately discussed in the results of
operations section of MD&A.

Consolidated Balance Sheets, page F-3
2. In future filings, please revi se to clearly label your long term debt as “convertible
subordinated debt,” as descri bed in the footnotes to your  financial statements.

Notes to Consolidated Financial Statements

Note 2.  Significant Accounting Policies, page F-6

Revenue Recognition, page F-8
3. Please tell us and revise future filings to clearly disclose your accounting policy for recognizing revenue from royalty arrang ements.  Please note that it should be
evident from your disclosure that the royalty revenue is from a related party.

Form 10-Q for the quarterly period ended March 31, 2007

Consolidated Statement of Cash Flows, page 5
4. We see that you currently present the cash dividend from SEN within operating
activities in your consolidated statement of cash flows.  Please tell us why you
should not record the dividend as a com ponent of net cash provided by investing
activities.  We reference paragraph 16(b) of SFAS 95 whic h states that returns of
investment in equity instruments are gene rally recorded as investing activities.

As appropriate, please respond to these co mments within 10 business days or tell
us when you will provide us with a response.  Please furnish a cover letter with your
response that keys your responses to our  comments and provides any requested
information.  Detailed cover le tters greatly facilitate our re view.  Please understand that
we may have additional comments after re viewing your responses to our comments.

  We urge all persons who are responsi ble for the accuracy an d adequacy of the
disclosure in the filing to be certain that the filing includes all in formation required under
the Securities Exchange Act of 1934 and th at they have provided all information

Mr. Bassett
Axcelis Technologies, Inc.
July 20, 2007 Page 3
investors require for an informed decision.  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 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 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 comme nts as a defense in any proceeding
initiated by the Commission or any person under the federal secu rities laws of the
United States.

In addition, please be advise d that the Division of Enfo rcement 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 Kristin Lochhead at (202) 551-3664 or me at (202) 551-3676 if you have questions.  In this regard, please do not hesitate to contact Martin James, Senior
Assistant Chief Accountant, at ( 202) 551-3671 with any other questions.

Sincerely,

Brian Cascio
Accounting Branch Chief