Re: Modification of Compensation of Chief Executive Officer and Chairman

Exhibit 10.1

Mary G. Puma

Chairman and CEO

Tel: (978) 787-4226

Fax: (978) 787-4090

May 1, 2009

Board of Directors

Axcelis Technologies, Inc.

c/o Stephen R. Hardis, Lead Director

108 Cherry Hill Drive

Beverly, Massachusetts 01915

Re: Modification of Compensation of Chief Executive Officer and Chairman

Dear Members of the Axcelis Board of Directors:

I am writing to propose that my base pay at Axcelis Technologies, Inc. (the “Company”) be reduced to a rate of $400,000 per year for the calendar years 2009 and 2010.  This amount represents a 20% reduction from my current rate of pay, which has been set forth in the Amended and Restated Employment Agreement between the Company and me effective November 6, 2007 (the “Employment Agreement”).  For the calendar year 2009, my rate of pay shall be reduced beginning wit