Arch Chemicals, Inc. Conference Call Announcement

A conference call to review 2009 results and to provide guidance for 2010 will be held on Thursday, February 4, 2010, at 11:00 a.m. (ET) by Michael E. Campbell, Chairman, President and CEO, Steven C. Giuliano, Senior Vice President and CFO, and Michael A. Cook, Senior Vice President of Global HTH Water Products. Prepared remarks will take about 20 minutes and will be followed by a question and answer period.

Financial and segment information will be released Thursday morning, February 4, before the market opens. The release will be available on First Call, Business Wire and Dow Jones News Service.

If you wish to participate, please call (877) 397-0298, access number 9422868, at least ten minutes before the call is scheduled to begin. From outside the U.S., please call (719) 325-4753, access number 9422868. The live Webcast of the call can be accessed on the home page of the Company’s Web site: http://www.archchemicals.com; it will be Windows Media Player and RealPlayer compatible.

A replay of the call will be available from 1:00 p.m. on Thursday, February 4, until 6:00 p.m. (ET) on Thursday, February 11. The replay number is (888) 203-1112, access number 9422868; from outside the U.S., please call (719) 457-0820, access number 9422868.

About Arch

Headquartered in Norwalk, Connecticut (USA), Arch Chemicals, Inc. is a global Biocides company with annual sales of approximately $1.5 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 concentration is in water treatment, hair and skin care products, treated wood, preservation and protection applications such as for paints and building products, and health and hygiene applications. Arch Chemicals operates in two segments: Treatment 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.