Arch Chemicals announces senior management appointments

NORWALK, CT, May 18, 2007 -- Arch Chemicals Inc. (NYSE: ARJ) announced that it has appointed two senior executives to expanded roles within the organization. Louis S. Massimo, Executive Vice President and Chief Financial Officer, has been promoted to the position of Executive Vice President and Chief Operating Officer. Steven C. Giuliano, Controller and Principal Accounting Officer, will be promoted to the position of Vice President and Chief Financial Officer.

Massimo has more than 13 years of experience with Arch (and its former parent company, Olin Corporation) during which time he has assumed increasing levels of responsibility in the areas of corporate accounting and finance, information technology, strategic planning and development, investor relations and corporate communications. In addition, he has led many of the Company's portfolio management activities involving acquisitions and divestitures. Massimo previously managed the Company's Hydrazine, Sulfuric Acid and Hickson & Welch businesses, and concurrent with his role as Chief Financial Officer, he more recently managed the Company's HTH Water Products business.

"As a member of Arch's senior leadership team, Louis has played a vital role in the successful execution and integration of all of our acquisitions since our founding. Over the past 18 months, he has led our efforts to significantly enhance the performance of the Water Products business, resulting in a dramatic margin improvement in 2006 while positioning this business for further profitable growth in 2007 and beyond," said Arch Chemicals' Chairman, President and CEO Michael E. Campbell. "I look forward to working with Louis to profitably grow Arch and achieve our full potential."

Giuliano has been Controller since Arch's founding in 1999 and has assumed increasing levels of responsibility in the areas of corporate finance and accounting, including SEC reporting and compliance. He has also played key roles with strategic acquisitions, dispositions of several Arch businesses and the Company's debt financings.

"Steve has done an outstanding job as Arch's Controller, and I look forward to his continued valuable contributions as a new member of our senior management team," added Campbell.

Meghan E. DeMasi, Arch's Assistant Controller who joined the Company in 2003, has been named to replace Giuliano as Controller.

Campbell continued, "I'm excited about the depth and experience of our management team and I am confident that the organizational changes announced today will enable us to continue delivering on our commitment to grow profitably and to enhance shareholder value."

Concurrent with the new appointments, Arch announced that Paul J. Craney, Executive Vice President, Treatment Products, has elected to retire from the Company by June 30, 2007. Craney has served with Arch (and Olin) since 1970. "We at Arch are deeply grateful to Paul for his many valuable contributions, and most importantly, for his leadership in positioning Arch to capitalize on future global growth opportunities, particularly in the Asia Pacific region," said Campbell.

Headquartered in Norwalk, Connecticut (USA), Arch Chemicals, Inc. is a global Biocides company with annual sales of approximately $1.4 billion. Arch and its subsidiaries provide innovative, chemistry-based solutions to control the growth of harmful microbes. The Company's concentration is in water, hair and skin care products, pressure-treated wood, paints and coatings, 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 and Africa.

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