Exhibit10.55

NALCO HOLDING COMPANY2004 STOCK INCENTIVEPLAN

RESTRICTED STOCK UNIT AGREEMENT

2006Grant

THIS AGREEMENT, is made effective as of February15,  2006 (the ‘‘**GrantDate**’’), between Nalco Holding Company (the‘‘**Company**’’) and Rodney F.Chase (the‘‘**Participant**’’).

R E C I T A L S:

WHEREAS,the Company has adopted the Plan (as defined below), the terms of whichare hereby incorporated by reference and made a part of this Agreement;and

WHEREAS, the Board of Directors of the Company (the‘‘Board’’) has determined that theParticipant be granted the Restricted Stock Units provided for hereinpursuant to the Plan and the terms set forth herein.

NOW,THEREFORE, in consideration of the mutual covenants hereinafter setforth, the parties agree asfollows:

1. Definitions. Whenever the followingterms are used in this Agreement, they shall have the meanings setforth below. Capitalized terms not otherwise defined herein shall havethe same meanings as in the Plan.

(a)‘‘**Plan**’’ means the NalcoHolding Company 2004 Stock Incentive Plan, as the same may be amended,supplemented or modified from time to time.

(b)‘‘**Restricted Stock Unit**’’means the unfunded, unsecured right of the Participant to receive ashare of the Company’s common stock, par value $0.01 per share(the‘‘**Shares**’’).

2. Grantof Restricted Stock Units. The Company hereby grants to theParticipant, subject to the terms and conditions of this Agreement andthe Plan, 3,670 Restricted Stock Units. The Participant shall notpossess any incidents of ownership (including, without limitation,dividend and voting rights) in Shares in respect of the RestrictedStock Units until such Restricted Stock Units have been distributed tothe Participant in the form ofShares.

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|  | 3.  | Delivery of Shares Underlying theRestricted Stock Units. |

(a) In General. Subject toSections 3(b), 3(c) and 3(d), (i) the Company shall issue or causethere to be transferred to the Participant on January  1,2008, a number of Shares equal to the aggregate number of RestrictedStock Units granted to the Participant under this Agreement.

(b)Change of Control. Notwithstanding the foregoing, upon aChange of Control, the Company shall issue or cause there to betransferred, to the extent not previously cancelled or forfeited, tothe Participant a number of Shares equal to the aggregate number ofRestricted Stock Units granted to the Participant under thisAgreement.

(c) Cancellation of Restricted Stock Units.Upon the issuance or transfer of Shares in accordance with this Section3, a number of Restricted Stock Units equal to the number of Sharesissued or transferred to the Participant shall be cancelled.

(d)Termination of Service on the Board of Directors. If theParticipant ceases to be a member of the Board of Directors of theCompany for any reason, the Restricted Stock Units shall be immediatelycanceled by the Company without any payment or other consideration.

(e) Registration or Qualification. Notwithstanding anyother provision of the Plan or this Agreement to the contrary, absentan available exemption to registration or qualification, a Restricted

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Stock Unit may not be delivered prior to thecompletion of any registration or qualification of the Restricted StockUnits or the Shares to which they relate under applicable state andfederal securities or other laws, or under any ruling or regulation ofany governmental body or national securities exchange that the Board orthe Company’s Compensation Committee(‘‘Committee’’) shall in its solereasonable discretion determine to be necessary or advisable.

(f)Certificates. As soon as practicable following the deliverydate of the Shares subject to the Restricted Stock Units, the Companyshall issue certificates in the Participant’s name for suchShares. However, the Company shall not be liable to the Participant fordamages relating to any delays in issuing the certificates to theParticipant, any loss by the Participant of the certificates, or anymistakes or errors in the issuance of the certificates or in thecertificates themselves

4. Legend onCertificates. The certificates representing the Shares issued tothe Participant upon the vesting of the Restricted Stock Units shall besubject to such stop transfer orders and other restrictions as theCommittee may deem reasonably advisable under the Plan or the rules,regulations, and other requirements of the Securities and ExchangeCommission, any stock exchange upon which such Shares are listed, anyapplicable federal or state laws or the Company’s Certificate ofIncorporation and Bylaws, and the Committee may cause a legend orlegends to be put on any such certificates to make appropriatereference to suchrestrictions.

5. Transferability. Unlessotherwise determined by the Committee, a Restricted Stock Unit may notbe assigned, alienated, pledged, attached, sold or otherwisetransferred or encumbered by the Participant otherwise than by will orby the laws of descent and distribution, and any such purportedassignment, alienation, pledge, attachment, sale, transfer orencumbrance shall be void and unenforceable against the Company or anyAffiliate; provided that the designation of a beneficiary shall notconstitute an assignment, alienation, pledge, attachment, sale,transfer or encumbrance.

6. Withholding. TheCompany or its Affiliate shall have the right to withhold from anypayment due or transfer made with respect to the Restricted Stock Unit,any applicable withholding taxes in respect of the Restricted StockUnit or any payment or transfer with respect to the Restricted StockUnit or under the Plan and to take such action as may be necessary inthe option of the Company to satisfy all obligations for the payment ofsuch taxes.

7. Securities Laws. Upon theacquisition of any Shares pursuant to the vesting of the RestrictedStock Units, the Participant will make or enter into such writtenrepresentations, warranties and agreements as the Committee mayreasonably request in order to comply with applicable securities lawsor with this Agreement.

8. Notices. Any noticeunder this Agreement shall be addressed to the Company in care of itsGeneral Counsel at the principal executive office of the Company and tothe Participant at the address appearing in the personnel records ofthe Company for the Participant or to either party at such otheraddress as either party hereto may hereafter designate in writing tothe other. Any such notice shall be deemed effective upon receiptthereof by the addressee.

9. Governing Law. ThisAgreement shall be governed by and construed in accordance with thelaws of the State of New York, without regard to conflicts oflaws.

10.    Restricted Stock Units Subject to thePlan. By entering into this Agreement the Participant agrees andacknowledges that the Participant has received and read a copy of thePlan. The Restricted Stock Units and the Shares received upon vestingare subject to the Plan. The terms and provisions of the Plan as it maybe amended from time to time are hereby incorporated by reference. Inthe event of a conflict between any term or provision contained hereinand a term or provision of the Plan, the applicable terms andprovisions of the Plan will govern andprevail

11.    Counterparts. This Agreement may beexecuted in any number of counterparts, each of which when so executedshall be deemed to be an original and all of which taken together shallconstitute one and the same agreement. Any counterpart or othersignature hereupon delivered by facsimile shall be deemed for allpurposes as constituting good and valid execution and delivery of thisAgreement by such party.

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IN WITNESS WHEREOF, this Agreement has beenexecuted and delivered by the partieshereto.

|  | NALCO HOLDING COMPANY |
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|  | By:/s/ Stephen N. Landsman                Its VicePresident, General Counsel & CorporateSecretary |
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|  | /s/ Rodney F.Chase                                Participant |
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