ATMI Treatment Systems Opens New Office in China; Expanding Customer Sales & Service Support in Songjiang, China.

DANBURY, Conn. -- ATMI, Inc. (Nasdaq: ATMI), a supplier of materials and materials packaging to the world's leading semiconductor manufacturers, today announced that ATMI Treatment Systems, its environmental abatement equipment business, has opened a new office in Songjiang, China, outside of Shanghai, to provide local support to its customers. The new office is located at:

ATMI, Inc.

Dingxin Mansion, Suite 102

Xiangfeng Road 221 Long #36

Songjiang District, Shanghai 201600

P. R. CHINA

Tel/Fax: [phone]

Steve Tsu, General Manager of the ATMI Treatment Systems business said, ``As the semiconductor industry grows in China, ATMI is building its local infrastructure to support our growing customer base. This office will better enable us to provide local sales and technical support along with spare parts logistics to semiconductor fabs around the Shanghai area.''

ATMI currently maintains an office in the Pudong district of Shanghai located at:

ATMI, Inc.

# 1202, Baoan Plaza

No. 800, Dongfang Rd

Pudong, Shanghai 200122

P. R. CHINA

Tel: [phone]

ATMI Treatment Systems offers a complete range of proven technology solutions for all process types and modules for a complete fab-wide abatement solution. As well as the existing Vector(R) (wet), Novapure(R) (dry), Guardian(R) (thermal), and CDO(R) integrated technology systems, ATMI Treatment Systems is introducing the Marathon(TM) 8500. The new Marathon(TM) combination abatement tool will offer unrivalled gas destruction efficiency in ultra-high volume applications, including epitaxial, low-k, LCD/Flat panel display CVD, and perfluorinated compounds (PFC) clean processes.

In October 2003, ATMI announced its objective to exit its non-core businesses, including ATMI Treatment Systems, by outright sale or joint venture and expects this to take place by the end of 2004. ATMI will be reallocating those resources to its core materials and materials packaging businesses.

ATMI provides specialty materials and materials packaging to the worldwide semiconductor industry. As the Source of Semiconductor Process Efficiency, ATMI helps customers improve wafer yields and lower operating costs. For more information, please visit atmi.com.

Statements contained herein that relate to ATMI's future performance, including, without limitation, statements with respect to ATMI's anticipated results of operations or level of business for 2004 or any other future period, are forward-looking statements within the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Such statements are based on current expectations only and are subject to certain risks, uncertainties, and assumptions, including, but not limited to: changes in semiconductor industry growth or ATMI's markets; competition, problems, or delays developing and commercializing new products; problems or delays in integrating acquired operations and businesses into ATMI; problems or delays associated with any restructuring activity, or implementing any strategy, including resolution of the various discontinued elements of ATMI's Technologies segment; and other factors discussed in ATMI's filings with the Securities and Exchange Commission. Such risks and uncertainties could cause actual results to differ from those projected. ATMI undertakes no obligation to publicly update or revise any forward-looking statements, whether because of new information, future events or otherwise.