Exhibit
        10.5
 
 AMENDMENT
        TO THE
 SUPPLEMENTAL
        CONTRIBUTING EMPLOYEE OWNERSHIP PLAN
 
 WHEREAS,
        Arch Chemicals, Inc. (the “Company”) sponsors a non-qualified deferred
        compensation plan known as the Supplemental Contributing Employee Ownership
        Plan
        (the “Plan”) for the benefit of certain salaried employees of Arch and other
        Employing Companies who may be eligible to participate in the Plan;
        and
 
 WHEREAS,
        in Section 7.1 of the Plan, the Company reserved the right to amend the Plan,
        in
        whole or in part, by action of the Compensation Committee of the Board;
        and
 
 WHEREAS,
        the American Jobs Creation Act of 2004 made substantial changes to the tax
        laws
        affecting non-qualified deferred compensation plans effective as of January
        1,
        2005, which changes were primarily codified in §409A of the Internal Revenue
        Code; and
 
 WHEREAS,
        the Internal Revenue Service issued preliminary guidance concerning Code
§409A
        in IRS Notice 2005-1 and in Proposed Treasury Regulations §1.409A-1 through -6
        (issued on October 4, 2005), which guidance authorized certain transition
        relief
        concerning plan documentation, deferral elections and distribution elections;
        and
 
 WHEREAS,
        the Company intends to more comprehensively amend and restate the Plan before
        December 31, 2006 (the end of the transition relief period), but in the meantime
        wishes to amend the Plan to take advantage of certain transition relief;
        and
 
 WHEREAS,
        the Compensation Committee of the Board delegated authority to the Vice
        President of Human Resources for the Company to amend the Plan as necessary
        or
        appropriate to comply with Code §409A,
 
 NOW,
        THEREFORE, the Plan is hereby amended as follows:
 
 1.  Except
        as
        otherwise provided in this amendment, and notwithstanding any other provisions
        in the Plan to the contrary, effective as of January 1, 2005, the Plan shall
        be
        deemed amended to the extent necessary to comply with Code §409A(a)(2), (3) and
        (4) with respect to amounts deferred pursuant to the Plan prior to January
        1,
        2005 and on and after January 1, 2005, except that benefits payable to
        participants who terminated employment and commenced benefit distributions
        prior
        to January 1, 2005 shall continue to be governed by the terms of the
        Plan
        in effect prior to January 1, 2005, and all Plan provisions shall be interpreted
        accordingly.
 
 2.  Notwithstanding
        Section 1, above, pursuant to Notice 2005-1, Q&A 19(c), as extended by the
        transition relief provided in Section XI, C of the Preamble to Proposed
        Regulations, and in accordance with procedures established by the Plan
        Administrator, the Plan is hereby amended effective as of January 1, 2005
        to the
        extent necessary to provide:
 
 (a)  for
        new
        payment elections with respect to amounts deferred prior to the election,
        provided the participant makes the election on or before December 31, 2005;
        and
 
 
 (b)  for
        new
        payment elections on or before December 31, 2006 with respect to both the
        time
        and form of payment of amounts subject to such elections, provided the
        participant makes any applicable election on or before December 31, 2006
        and
        provided the election applies only to amounts that would not otherwise be
        payable in 2006 and does not cause an amount to be paid in 2006 that would
        not
        otherwise be payable in 2006.
 
 
 This
        amendment shall supersede the provisions of the Plan to the extent that those
        provisions are inconsistent with the provisions of this amendment. Except
        as
        amended hereby, and subject to operational compliance with Notice 2005-1
        and
        applicable Treasury Regulations, the terms of the Plan remain in full force
        and
        effect.
 
 The
        foregoing amendments shall be effective in accordance with their
        terms.
 
 
 IN
        WITNESS WHEREOF, the undersigned has set his hand as of the third day of
        November, 2005.


ARCH
                CHEMICALS, INC.By:
              /s/Hayes
                AndersonIts:
              Vice President, Human ResourcesDuly
                Authorized