ARJ Arch Chemicals

Arch Chemicals, Inc. (NYSE:ARJ) will release second quarter 2011 summarized financial information on Friday morning, August 5, before the market opens. The release will be available on First Call, GlobeNewswire and Dow Jones News Service. The Company expects to file its quarterly report on Form 10-Q shortly thereafter.

Arch Chemicals will not be hosting a conference call to review its second quarter results and 2011 outlook due to the July 15, 2011 commencement of a tender offer by LG Acquisition Corp., a wholly owned subsidiary of Lonza Group Ltd., to acquire 100 percent of Arch Chemicals' outstanding shares of common stock.

About Arch

Headquartered in Norwalk, Connecticut (USA), Arch Chemicals, Inc. is a global Biocides company with annual sales of over $1 billion. Arch and its subsidiaries provide innovative, chemistry-based and related solutions to destroy or to selectively inhibit the growth of harmful microorganisms. The Company is concentrated in the areas of water treatment, personal care, health and hygiene, industrial preservation and protection, and wood treatment. Arch Chemicals operates in two segments:  Biocides Products and Performance Products. Together with its subsidiaries, Arch has approximately 3,000 employees and manufacturing and customer-support facilities in North and South America, Europe, Asia, Australia and Africa. For more information, visit the Company's Web site at http://www.archchemicals.com.

CONTACT: Investor Contact:
         Mark E. Faford  (203) 229-3820
         Press Contact:
         Dale N. Walter  (203) 229-3033