Cabot Microelectronics Appoints Jean Pol Delrue as Vice President, European Business Region

AURORA, Ill.--(BUSINESS WIRE)--Aug. 4, 2004--Cabot Microelectronics Corp. (Nasdaq:CCMP), the leading supplier of chemical mechanical planarization (CMP) slurries to the semiconductor industry, announced today the appointment of Jean Pol Delrue to the position of Vice President, European Business Region. Mr. Delrue will report directly to William P. Noglows, Cabot Microelectronics' Chairman and Chief Executive Officer.

Mr. Delrue joined Cabot Microelectronics in 2001 as the European Business Manager and has led the company's business initiatives in the European region, including developing and implementing regional business strategies, as well as managing customer and distributor relationships.

"Jean Pol has provided Cabot Microelectronics with sound business leadership combined with a strong customer and market focused management approach, and has assisted in achieving our objectives in Europe," stated Mr. Noglows. "He has over 23 years of global experience in the semiconductor industry and significant expertise in the semiconductor capital equipment business. His proven experience has been critical to our growth in Europe and will continue to play a pivotal role in our company's success."

"Having worked with Cabot Microelectronics for three years, I am very pleased to accept the position of Vice President, European Business Region," stated Mr. Delrue. "I'm very excited about the future potential of Cabot Microelectronics as the technology leader in the field of CMP slurries. I am looking forward to building on our strong customer relationships in the European region and continuing to anticipate our customers' needs."

Prior to joining Cabot Microelectronics, Mr. Delrue worked at Ebara Precision Machinery Europe, serving as the Vice President for CMP equipment. He also served as the Business and Technical Development Director and Member of the Management Board at Riber Group, a supplier of molecular beam epitaxial products and services to the compound semiconductor industry.

Mr. Delrue holds an Executive Masters in Business Administration from the Centre de Perfectionnement des Affaires in Paris, France, a post doctorate degree in chemical engineering from Stanford University and a Ph.D. in physical chemistry from Belgium's University of Mons.

About Cabot Microelectronics

Cabot Microelectronics Corporation, headquartered in Aurora, Illinois, is the leading supplier of CMP slurries for polishing various materials used in semiconductor manufacturing processes. The company's products play a critical role in the production of the most advanced semiconductor devices, enabling the manufacture of smaller, faster and more complex devices by its customers. For more information about Cabot Microelectronics Corporation, visit www.cabotcmp.com or contact Mr. David H. Li, Director of Investor Relations at (630) 499-2600.

Safe Harbor Statement

This news release may include statements that constitute "forward-looking statements" within the meaning of federal securities regulations. These forward-looking statements include statements related to future sales and operating results, company and industry growth and trends, growth of this market, international events, product performance, new product introductions and development of new products and technologies by Cabot Microelectronics. These forward-looking statements involve a number of risks, uncertainties, and other factors, including those described from time to time in Cabot Microelectronics' filings with the Securities and Exchange Commission (SEC), that could cause actual results to differ materially from those described by these forward-looking statements. In particular, see "Risks Relating to Our Business" in Management's Discussion and Analysis in our quarterly report on Form 10-Q for the quarter ended March 31, 2004, and our Annual Report on Form 10-K for the fiscal year ended September 30, 2003, both filed with the SEC. Cabot Microelectronics Corporation assumes no obligation to update this forward-looking information.

David H. Li

(Investor Relations),

630-499-2600