ARJ Arch Chemicals

The Arch Chemicals, Inc. Board of Directors on January 27, 2011 declared a quarterly dividend of 20-cents on each share of Arch Chemicals (NYSE:ARJ) common stock. The dividend is payable on March 15, 2011 to shareholders of record at the close of business on February 15, 2011.

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 selectively destroy and control the growth of harmful microbes. The Company's businesses are concentrated in water treatment, hair and skin care products, wood treatment, preservation and protection applications, such as for paints and building products, and health and hygiene applications. 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.

CONTACT: Investor contact: Mark E. Faford
         (203) 229-3820
         mefaford@archchemicals.com
         
         Press contact: Dale N. Walter
         (203) 229-3033
         dnwalter@archchemicals.com