UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14D-9

SOLICITATION/RECOMMENDATION

STATEMENT UNDER SECTION 14(d)(4) OF THE

SECURITIES EXCHANGE ACT OF 1934

(AMENDMENT No. 5)

Arch Chemicals, Inc.

(Name of Subject Company)

Arch Chemicals, Inc.

(Name of Person Filing Statement)

COMMON STOCK, PAR VALUE $1.00 PER SHARE

(Title of Class of Securities)

03937R102

(CUSIP Number of Class of Securities)

Joseph P. Lacerenza, Esq.

Secretary

Arch Chemicals, Inc.

501 Merritt 7

P.O. Box 5204

Norwalk, CT 06856-5204

(203) 229-2900

(Name, address and telephone numbers of person authorized to receive notices and communications on behalf of the persons filing statement)

With copies to:

Robert I. Townsend, III, Esq.

Damien R. Zoubek, Esq.

Cravath, Swaine & Moore LLP

Worldwide Plaza

825 Eighth Avenue

New York, NY 10019

Telephone: (212) 474-1000

[   ] Check the box if the filing relates solely to preliminary communications made before the commencement of a tender offer.

This Amendment No. 5 (this “Amendment”) amends and supplements the Solicitation/Recommendation Statement on Schedule 14D-9 of Arch Chemicals, Inc., a Virginia corporation (the “Company”), initially filed on July 15, 2011, as amended by Amendment No. 1 thereto filed on July 20, 2011, Amendment No. 2 thereto filed on July 26, 2011, Amendment No. 3 thereto filed on July 29, 2011 and Amendment No. 4 thereto filed on August 4, 2011 (the “Initial Schedule 14D-9”). The Initial Schedule 14D-9 relates to the cash tender offer by LG Acquisition Corp., a Virginia corporation (the “Offeror”) and an indirect, wholly owned subsidiary of Lonza Group Ltd., a company organized under the laws of Switzerland (“Parent”), disclosed in a Tender Offer Statement on Schedule TO, dated July 15, 2011 (the “Schedule TO”), filed with the Securities and Exchange Commission, to purchase all of the outstanding common stock, par value $1.00 per share, of the Company (the “Company Common Stock”), at a price of $47.20 per share of Company Common Stock, net to the seller in cash, without interest thereon and less any required withholding taxes, upon the terms and subject to the conditions set forth in the Offer to Purchase, dated July 15, 2011 and in the related Letter of Transmittal, which were filed with the Schedule TO as Exhibits (a)(1)(A) and (a)(1)(B) thereto, in each case as may be amended or supplemented. Except as otherwise set forth below, the information set forth in the Initial Schedule 14D-9 remains unchanged and is incorporated by reference as relevant to the items in this Amendment. Capitalized terms used but not otherwise defined herein have the meanings ascribed to such terms in the Initial Schedule 14D-9.

ITEM 9.     EXHIBITS

Item 9 of the Initial Schedule 14D-9 is hereby amended and supplemented by adding the following Exhibit:

Exhibit No.	Description
(a)(5)(E)	Form of Letter to US Employees Regarding the Extension of the Offer, dated August 12, 2011.

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SIGNATURE

After due inquiry and to the best of my knowledge and belief, I certify that the information set forth in this Amendment is true, complete and correct.

Arch Chemicals, Inc.
By:	/s/ Joseph P. Lacerenza
	Name:  Joseph P. Lacerenza
	Title:    Senior Deputy General Counsel and Secretary

Dated:  August 12, 2011

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