Aspen Technology Names Mark Fusco President & CEO; Fusco brings track record of growing business with global customers and strong background in professional services.

CAMBRIDGE, Mass. -- Aspen Technology, Inc. (Nasdaq: AZPN) today announced that its Board of Directors has named Mark Fusco as President and Chief Executive Officer of the company. Fusco, who has served on AspenTech's Board of Directors for the past year, will assume his responsibilities at AspenTech effective January 3, 2005.

Fusco has spent the past 14 years in executive management positions delivering IT consulting and software development capabilities for global companies. He currently serves as President and Chief Operating Officer for Ajilon Consulting U.S., an IT consulting subsidiary of Adecco SA with more than 4,000 employees globally. Prior to his position at Ajilon, he was the President and Co-Founder of Software Quality Partners (SQP), an IT consulting firm specializing in software quality assurance and testing. SQP was sold to Ajilon in 1999, after Fusco led the firm to significant growth. Fusco also served as President of Analysis and Computer Systems Inc., a provider of simulation equipment to the military and defense industry.

"Mark's expertise in building and enhancing relationships with large customers and in selling and implementing complex solutions will be extremely valuable as we seek to increase the adoption of our new aspenONE solutions and make Enterprise Operations Management (EOM) a reality for our customers," said Charles Kane, Chief Financial Officer and Interim CEO of AspenTech. "Through his active participation on AspenTech's Board, Mark has developed a strong understanding of the company's strengths, as well as its challenges, which will enable him to immediately focus on improving our sales and services efforts."

"Over the past 23 years AspenTech has established a customer franchise and product portfolio that is unmatched in the process industries," said Mark Fusco, incoming President & CEO of AspenTech. "I am very excited about the opportunity to leverage these assets and expand the company's footprint with our major customers. I believe that the company is poised to benefit from the roll-out of our new aspenONE solutions and the process industries' need to improve their operational performance. I look forward to working closely with our employees, customers, partners and shareholders and driving the future direction of this company."

Mark is a graduate of Harvard College and Harvard Business School. He played professional ice hockey and was a member of the 1984 United States Olympic Ice Hockey team.

Conference Call and Webcast

The company will hold a conference call to discuss this announcement at 4:30 p.m. Eastern Time on Thursday, December 9, 2004. The live dial-in number for the call is [phone]. The call will also be webcast live on AspenTech's website: http://www.aspentech.com. Investors can access the call by clicking on the "Webcast" link under the Investor Relations section of the site. A replay of the call will be archived on AspenTech's website and will also be available via telephone, beginning at 6:30 p.m. eastern time on December 9, 2004, by dialing [phone] and entering in confirmation code: 2808659.

About Aspen Technology

Aspen Technology, Inc. provides industry-leading software and implementation services that enable process companies to use simulation models to increase efficiency and profitability. aspenONE, a new generation of software solutions from the Company, represents a major step forward in helping process manufacturers achieve their strategic operational excellence initiatives. The first comprehensive offering to address the demands of the Enterprise Operations Management (EOM) market, aspenONE provides companies with integrated systems that enable them to manage and optimize their operational performance. Over 1,500 leading companies already rely on the Company's software, including Aventis, Bayer, BASF, BP, ChevronTexaco, Dow Chemical, DuPont, ExxonMobil, Fluor, GlaxoSmithKline, Shell, and Total. For more information, visit www.aspentech.com.

The fourth paragraph of this press release contains forward-looking statements for purposes of the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. For this purpose, any statement using the term "will," "should," "could," "anticipates," "believes" or a comparable term is a forward-looking statement. Actual results may vary significantly from AspenTech's expectations based on a number of risks and uncertainties, including: AspenTech's lengthy sales cycle which makes it difficult to predict quarterly operating results; the FTC proceeding challenging AspenTech's acquisition of Hyprotech; fluctuations in AspenTech's quarterly operating results; AspenTech's dependence on customers in the cyclical chemicals, petrochemicals and petroleum industries; AspenTech's ability to raise additional capital as required; AspenTech's ability to integrate the operations of acquired companies; intense competition; AspenTech's need to develop and market products successfully; reliance on relationships with strategic partners; and other risk factors described from time to time in AspenTech's periodic reports and registration statements filed with the Securities and Exchange Commission. AspenTech cannot guarantee any future results, levels of activity, performance, or achievements. Moreover, neither AspenTech nor anyone else assumes responsibility for the accuracy and completeness of any forward-looking statements. AspenTech undertakes no obligation to update any of the forward-looking statements after the date of this press release.

AspenTech, aspenONE and the Aspen logo are trademarks of Aspen Technology, Inc., Cambridge, Mass.