**Exhibit          31.2**

| 1.     | I                    have reviewed this quarterly report on Form 10-Q of Arch Chemicals,                    Inc.;                                                                                                                                                                                                                                                                                                                                                                                       |
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| 2.     | Based                      on my knowledge, this report does not contain any untrue statement                      of a                      material fact or omit to state a material fact necessary to                      make the                      statements made, in light of the circumstances under which                      such statements                      were made, not misleading with respect to the period covered                      by this                      report; |

| 3. | Based                      on my knowledge, the financial statements, and other financial                      information                      included in this report, fairly present in all material respects                      the                      financial condition, results of operations and cash flows of                      the                      registrant as of, and for, the periods presented in this                      report; |
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| 4. | The                      registrant’s other certifying officer and I are responsible for                      establishing and maintaining disclosure controls and procedures                      (as                      defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and                      internal                      control over financial reporting (as defined in Exchange Act                      Rules                      13a-15(f) and 15d-15(f)) for the registrant and                      have: |
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|   | a. | Designed                      such disclosure controls and procedures, or caused such disclosure                      controls and procedures to be designed under our supervision,                      to ensure                      that material information relating to the registrant, including                      its                      consolidated subsidiaries, is made known to us by others within                      those                      entities, particularly during the period in which this report                      is being                      prepared; |
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|   | b. | Designed                      such internal control over financial reporting, or caused such                      internal                      control over financial reporting to be designed under our supervision,                      to                      provide reasonable assurance regarding the reliability of financial                      reporting and the preparation of financial statements for external                      purposes in accordance with generally accepted accounting                      principles; |
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|   | c. | Evaluated                      the effectiveness of the registrant’s disclosure controls and procedures                      and presented in this report our conclusions about the effectiveness                      of                      the disclosure controls and procedures, as of the end of the                      period                      covered by this report based on such evaluation;                      and |
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|   | d. | Disclosed                      in this report any change in the registrant’s internal control over                      financial reporting that occurred during the registrant’s most recent                      fiscal quarter (the registrant’s fourth fiscal quarter in the case of an                      annual report) that has materially affected, or is reasonably                      likely to                      materially affect, the registrant’s internal control over financial                      reporting; and |
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| 5. | The                      registrant’s other certifying officer and I have disclosed, based on our                      most recent evaluation of internal control over financial reporting,                      to                      the registrant’s auditors and the audit committee of registrant’s board of                      directors (or persons performing the equivalent                      functions): |
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|   | a. | All                      significant deficiencies and material weaknesses in the design                      or                      operation of internal controls over financial reporting which                      are                      reasonably likely to adversely affect the registrant’s ability to record,                      process, summarize and report financial information;                      and |
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|   | b. | Any                      fraud, whether or not material, that involves management or                      other                      employees who have a significant role in the registrant’s internal control                      over financial reporting. |
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|         |                                             | /s/Louis                      S. Massimo |
|         | Louis                        S. Massimo          |
|         | Chief                          Financial Officer |

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