FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person* Walden Rick L. (Last) (First) (Middle) C/O ARCH CHEMICALS, INC., 501 MERRITT 7 (Street) NORWALK CT 06851 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 09/29/2009	3. Issuer Name and Ticker or Trading Symbol ARCH CHEMICALS INC [ARJ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director 10% Owner X Officer (give title below) Other (specify below) Sr VP, Biocides, Perf. Product	5. If Amendment, Date of Original Filed (Month/Day/Year)
			6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock $1 Par Value (1)	3,339.9922	I	By CEOP Trustee

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Excercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Phantom Stock Units (2)	(2)	(2)	Common Stock	1,850	$ (3)	D
Phantom Stock Units (2)	12/31/2013(4)	12/31/2013(4)	Common Stock	1,850	$ (3)	D
Phantom Stock Units	12/31/2014(4)	12/31/2014(4)	Common Stock	3,100	$ (3)	D

Explanation of Responses:

1. The figure shown represents shares of Arch Common Stock acquired on a periodic basis under the Contributing Employee Ownership Plan (CEOP), a tax conditioned plan, and held as of 09/29/2009 in the Arch Common Stock Fund of the CEOP, in transactions exempt under Rule 16b-3, and is based on information provided by the Plan Administrator .

2. Phantom share units which are paid out in cash at maturity if the officer is still employed by the company . These phantom share units were granted on February 5, 2004 and vest on December 31, 2009.

3. This security converts to common stock on a 1 for 1 basis

4. Phantom share units granted under the Arch Chemicals, Inc 1999 Long Term Incentive Plan which may be paid out in cash or stock at an earlier date provided certain financial measures are reached by the company. Otherwise, they are paid out in cash or stock at maturity if the officer is still employed by the company, subject to plan provisions.

	Joseph P. Lacerenza, Attorney in Fact	09/30/2009
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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EX-24

(For Executing SEC Forms 3, 4, 5 and 144) KNOW ALL BY THESE PRESENTS, that the undersigned hereby constitutes and appoints each of Sarah A. O'Connor, J. P. Lacerenza and Steven C. Giuliano, or either of them signing singly, and with full power of substitution, the undersigned's true and lawful attorney-in-fact to: (1) prepare, execute in the undersigned's name and on the undersigned's behalf, and submit to the U.S. Securities Commission (the "SEC") a Form ID, including amendments thereto, and any other documents necessary to obtain codes and passwords enabling the undersigned to make electronic filings with the SEC of reports required by Section 16 (a) of the Securities Exchange Act of 1934 or any rule or regulation of the SEC; (2) execute for and on behalf of the undersigned, in the undersigned's capacity as an officer and/or director of Arch Chemicals, Inc. (the "Company") Forms 3, 4 and 5 and any amendments thereto in accordance with Section 16(a) of the Securities Exchange Act of 1934 and the rules thereunder; (3) execute Form 144 and any amendments thereto under Rule 144 promulgated under the Securities Act of 1933 relating to transactions involving securities of the Company for and on behalf of the undersigned; (4) do and perform any and all acts which may be necessary or desirable to complete the execution of any such Form 3, 4, 5 or 144 or amendment and the filing of such form or amendment with the United States Securities and Exchange Commission, any other authority and any stock exchange; and (5) take any other action of any type whatsoever in connection with the foregoing which, in the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required by, the undersigned, it being understood that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to this Power of Attorney shall be in such form and shall contain such terms and conditions as such attorney-in-fact may approve in such attorney-in-fact's discretion. The undersigned hereby grants to each such attorney-in-fact full power and authority to do and perform all and every act and thing whatsoever requisite, necessary and proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorneys-in-fact, or attorney-in-fact's substitute or substitutes, shall lawfully do or cause to be done by virtue of this power of attorney and the rights and powers herein granted. The undersigned acknowledges that the foregoing attorneys-in-fact, in serving in such capacity at the request of the undersigned, are not assuming, nor is the Company assuming, any of the undersigned's responsibilities to comply with Section 16 of the Securities Exchange Act of 1934 or with Rule 144 of the Securities Act of 1933. This Power of Attorney shall remain in full force and effect until the undersigned is no longer required to file Forms 3, 4, 5 and 144 with respect to the undersigned's holdings of and transactions in securities issued by the Company, unless earlier revoked by the undersigned in a signed document delivered to the foregoing attorneys-in-fact. IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed effective as of September 29, 2009. ________________________________ Rick Walden ________________________________ Print Name