Exhibit 23

Consent of Independent Registered Public Accounting Firm

The Board of Directors

Arch Chemicals, Inc.:

We consent to the incorporation by reference in the registration statement (Nos. 333-71721, 333-54098, 333-133815, 333-133816 and 333-159307) on Form S-8 of Arch Chemicals, Inc. of our report dated February 19, 2010, with respect to the consolidated balance sheets of Arch Chemicals, Inc. and its subsidiaries as of December 31, 2009 and 2008, and the related consolidated statements of income, shareholders’ equity and comprehensive income (loss), and cash flows for each of the years in the three-year period ended December 31, 2009 and the effectiveness of internal control over financial reporting as of December 31, 2009, which report appears in the December 31, 2009 annual report on Form 10-K of Arch Chemicals, Inc.

Our report on the consolidated financial statements refers to the adoption of Financial Accounting Standards Board (FASB) Interpretation No. 48, Accounting for Uncertainty in Income Taxes (included in FASB ASC Topic 740, Income Taxes) in 2007.

/s/ KPMG LLP

Stamford, Connecticut

February 19, 2010