UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


         -------------------------------------------------------------

                                    FORM 11-K
 (Mark One)

     [X]       Annual report pursuant to Section 15(d) of the
               Securities Exchange Act of 1934

               For the fiscal year ended December 31, 2005

                                        OR

     [ ]       Transition report pursuant to Section 15(d)
               of the Securities Exchange Act of 1934

               For the transition period from _____ to _____


Commission File Number 1-11377

CINERGY CORP. UNION EMPLOYEES' SAVINGS INCENTIVE PLAN./


                          CINERGY CORP. UNION EMPLOYEES'
                             SAVINGS INCENTIVE PLAN
                             139 East Fourth Street
                             Cincinnati, Ohio 45202


              (Full title of the Plan and the address of the Plan,
                 if different from that of the issuer named below)

                                  CINERGY CORP.
                             139 East Fourth Street
                             Cincinnati, Ohio 45202

              (Name of issuer of the common stock issued pursuant to the
               Plan and the address of its principal executive office)





CINERGY CORP.
UNION EMPLOYEES' SAVINGS INCENTIVE PLAN

TABLE OF CONTENTS
- ----------------------------------------------------------------------------

                                                                        Page

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM                   1

FINANCIAL STATEMENTS:

   Statements of Net Assets Available for Benefits as of
     December 31, 2005 and 2004                                           2

   Statements of Changes in Net Assets Available for Benefits Years Ended
     December 31, 2005 and 2004                                           3

   Notes to Financial Statements                                         4-10

SUPPLEMENTAL SCHEDULE--                                                   11

   Form 5500, Schedule H, Part IV, Line 4i--Schedule of Assets
     (Held at End of Year) as of December 31, 2005                        12

   NOTE:    All other schedules required by Section 2520.103-10 of the
            Department of Labor's Rules and Regulations for Reporting and
            Disclosure under the Employee Retirement Income Security Act of 1974
            have been omitted because they are not applicable.

SIGNATURE                                                                S-1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM                 E-1




REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM


To the Benefits Committee of Cinergy Corp.
Cincinnati, Ohio

We have audited the accompanying statements of net assets available for benefits
of the Cinergy Corp. Union Employees' Savings Incentive Plan (the "Plan") as of
December 31, 2005 and 2004, and the related statements of changes in net assets
available for benefits for the years then ended. These financial statements are
the responsibility of the Plan's management. Our responsibility is to express an
opinion on these financial statements based on our audits.

We conducted our audits in accordance with standards of the Public Company
Accounting Oversight Board (United States). Those standards require that we plan
and perform the audit to obtain reasonable assurance about whether the financial
statements are free of material misstatement. The plan is not required to have,
nor were we engaged to perform, an audit of its internal control over financial
reporting. Our audits included consideration of internal control over financial
reporting as a basis for designing audit procedures that are appropriate in the
circumstances, but not for the purpose of expressing an opinion on the
effectiveness of the Plan's internal control over financial reporting.
Accordingly, we express no such opinion. An audit also includes examining, on a
test basis, evidence supporting the amounts and disclosures in the financial
statements, assessing the accounting principles used and significant estimates
made by management, as well as evaluating the overall financial statement
presentation. We believe that our audits provide a reasonable basis for our
opinion.

In our opinion, such financial statements present fairly, in all material
respects, the net assets available for benefits of the Plan as of December 31,
2005 and 2004, and the changes in net assets available for benefits for the
years then ended in conformity with accounting principles generally accepted in
the United States of America.

Our audits were conducted for the purpose of forming an opinion on the basic
financial statements taken as a whole. The supplemental schedule of assets (held
at end of year) as of December 31, 2005 is presented for the purpose of
additional analysis and is not a required part of the basic financial
statements, but is supplementary information required by the Department of
Labor's Rules and Regulations for Reporting and Disclosure under the Employee
Retirement Income Security Act of 1974. This schedule is the responsibility of
the Plan's management. Such schedule has been subjected to the auditing
procedures applied in our audit of the basic 2005 financial statements and, in
our opinion, is fairly stated in all material respects when considered in
relation to the basic financial statements taken as a whole.


Cincinnati, Ohio
June 23, 2006




CINERGY CORP.
UNION EMPLOYEES' SAVINGS INCENTIVE PLAN

STATEMENTS OF NET ASSETS AVAILABLE FOR BENEFITS
DECEMBER 31, 2005 AND 2004
- ----------------------------------------------------------------------------


ASSETS                                               2005              2004

CURRENT ASSETS:
  Investments--at fair value (see Notes 3 and 4):
    Plan interest in Cinergy Corp. Common
     Stock Master Trust                          $192,981,181      $179,340,965
    Mutual funds                                   87,571,579        81,826,463
    Interest bearing cash                          12,063,763        14,391,459
    Loans to participants                          11,929,541        11,004,614
    Common/collective trusts                        4,225,240         3,381,365
                                                  ------------      -----------


           Total investments                      308,771,304       289,944,866

  Employer's contribution receivable                1,332,937           647,708
                                                  -------------     -----------

NET ASSETS AVAILABLE FOR BENEFITS                $310,104,241      $290,592,574
                                                ==============     ============


See notes to financial statements.




CINERGY CORP.
UNION EMPLOYEES' SAVINGS INCENTIVE PLAN

STATEMENTS OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS
YEARS ENDED DECEMBER 31, 2005 AND 2004
- ---------------------------------------------------------------------------


                                                    2005               2004

ADDITIONS--
  Additions to net assets attributed to:
    Investment income:
      Plan interest in Cinergy Corp. Common
        Stock Master Trust (see Note 4)       $  12,745,334     $    20,285,354
      Net appreciation in fair value of
        investments (see Note 4)                  2,715,321           5,561,187
      Interest and dividends                      4,606,104           3,181,627
                                               ------------      --------------
           Net investment income                 20,066,759          29,028,168

  Contributions:
    Participant                                  11,679,190           9,573,341
    Employer                                      5,604,761           4,909,607
    Rollover                                         36,688             345,126
                                               ------------      --------------
           Total additions                       37,387,398          43,856,242
                                               ------------      --------------

DEDUCTIONS:
  Deductions from net assets attributed to:
    Benefits paid to participants              (15,296,249)        (10,050,166)
    Administrative fees                            (50,365)            (52,000)
    Dividends paid in cash                        (787,230)           (659,367)
    Deemed distributions of loans to participants  (41,203)            (21,096)
                                               ------------      --------------

           Total deductions                    (16,175,047)        (10,782,629)

  Net increase prior to transfers                21,212,351          33,073,613
  Interplan transfers (see Note 2)              (1,700,684)         (2,014,523)
                                               ------------      --------------
                                                 19,511,667          31,059,090

NET ASSETS AVAILABLE FOR BENEFITS:
  Beginning of year                             290,592,574         259,533,484
                                               ------------      --------------


  End of year                                  $310,104,241        $290,592,574
                                             ==============      ==============


See notes to financial statements.




CINERGY CORP.
UNION EMPLOYEES' SAVINGS INCENTIVE PLAN

NOTES TO FINANCIAL STATEMENTS
DECEMBER 31, 2005 AND 2004
- --------------------------------------------------------------------------


1.    PLAN DESCRIPTION

      The following description of the Cinergy Corp. Union Employees' Savings
      Incentive Plan (the "Plan") provides only general information.
      Participants should refer to the Plan Document for a more complete
      description of the Plan's provisions.

      General--The Plan is a defined contribution plan covering union employees
      of Cinergy Corp. and subsidiaries (collectively, the "Company") who are
      represented by the following collective bargaining organizations:

         The Utility Workers Union, Local 600

         The International Brotherhood of Electrical Workers, Local 1347

         The United Steelworkers of America, Local 12049 and Local 14214

         The Paper, Allied-Industrial, Chemical and Energy Workers, Local 4-1

         The Employees' Representation Association

         Unite, Local 2024

         Unite, Local 1093

      The Plan is administered by the Cinergy Corp. Benefits Committee and
      trusteed by the Fidelity Management Trust Company ("Fidelity") and the
      U.S. Trust Company of California N.A. ("US Trust"). The Plan is subject to
      the provisions of the Employee Retirement Income Security Act of 1974
      ("ERISA"), as amended. A portion of the administrative expenses of the
      Plan are paid by the Company.

      Contributions--The Company automatically enrolls new full time employees
      eligible for the Plan at a 3% deferral rate. The contributions made to the
      plan on the employee's behalf will be invested in one or more funds
      selected in accordance with procedures established by the Plan
      administrator. If an employee chooses not to participate, Fidelity, the
      recordkeeper, must be contacted by the employee to change the deferral
      rate to 0%.

      Under the Plan, the pre-tax contribution limit is 50% of annual base
      compensation up to the Internal Revenue Service ("IRS") maximum each year.
      In addition, a participant may make after-tax contributions up to 15% of
      annual base compensation. Pre-tax and after-tax contributions are subject
      to certain limitations. The pre-tax and after-tax contributions are
      invested by the trustee, as directed by each participant, in one or more
      investment funds, including the Cinergy Corp. Common Stock Master Trust.

      The Company matches 100% of the first 3% of pre-tax contributions from
      base pay plus 50% of the next 2% of pre-tax contributions from base pay.
      An additional incentive match will be a maximum of 1% of base pay based
      upon meeting corporate goals. Only employees making pre-tax contributions
      will receive the incentive match. All employer contributions are invested
      by the trustee in the Cinergy Corp. Common Stock Master Trust.

      The Company, at its discretion can make a profit sharing contribution to
      the Plan for eligible employees for the plan year in an amount determined
      by the Company. In 2005 and 2004, the amount of the Deferred Profit
      Sharing contributions were $537,313 and $135,431, respectively.

      Participants who are age 50 or older by the end of the year, may
      contribute an additional pre-tax amount over and above the IRS limits each
      year. For 2005 and 2004, the IRS allowed participants over the age of 50
      to contribute up to an additional $4,000 and $3,000 over and above the
      $14,000 and $13,000 pre-tax limit, respectively. Cinergy will not provide
      a base company match or incentive match on these additional contributions.

      Vesting--Participants are immediately vested in all contributions and
      earnings thereon, with the exception of Deferred Profit Sharing
      Contributions made by the Company which are vested after three years of
      service. However, the dividends on the Cinergy Corp. common stock on
      Deferred Profit Sharing Contributions are vested immediately.

      Participant Accounts--Each participant's account is credited with the
      participant's contribution and allocation of the Company's contribution
      and Plan earnings. Allocations are based on the participant's account
      balance or contribution percentage as defined in the Plan Document. The
      benefit to which a participant is entitled is the benefit that can be
      provided from the participant's vested account.

      A participant may elect or change investment funds and/or the contribution
      allocation percentage among funds at any time.

      Payment of Benefits--Participants are generally eligible to receive
      distributions of assets from the Plan upon termination of employment
      including retirement, death, or disability. Distributions are paid in a
      lump sum for vested benefits of $1,000 or less. Distributions are paid in
      a lump sum or up to ten annual installments (at the election of the
      participant) for vested benefits greater than $1,000. Active participants
      are also eligible to apply to the Plan administrator for "hardship"
      withdrawals from their pre-tax account in accordance with Plan provisions.

      Participant Loans--Subject to certain limitations, participants may apply
      for loans from their pre-tax account balances. Interest on the loan is set
      at the prime rate plus 1% at the time of borrowing, and the loans are
      secured by the balance in the participant's account. Loans are to be
      repaid within 54 months through regular payroll deductions.

2.    SIGNIFICANT ACCOUNTING POLICIES

      Basis of Accounting--The accompanying financial statements of the Plan are
      prepared on an accrual basis.

      Investment Valuation and Income Recognition--Investments are stated at
      fair value. Shares of registered investment companies are valued at quoted
      redemption prices, which represent the net asset value of shares held by
      the Plan at year-end. Company common stock is valued at its quoted market
      price. Participant loans are valued at cost, which approximates fair
      value.

      Purchases and sales of securities are recorded on a trade-date basis.
      Interest income is recorded on the accrual basis. Dividends are recorded
      on the ex-dividend date.

      Transfers of assets between the Plan and the Cinergy Corp. Non-Union
      Employees' 401(k) Plan and Cinergy Corp. Union Employees' 401(k) Plan
      occur as a result of changes in employee status between the union
      classification and the exempt and non-exempt classifications. Such
      transfers are reflected as interplan transfers on the statement of changes
      in net assets available for benefits.

      Use of Estimates--The preparation of financial statements in conformity
      with accounting principles generally accepted in the United States
      requires management to make estimates and assumptions that affect the
      reported amounts of assets and liabilities and changes therein, and
      disclosure of contingent assets and liabilities at the date of the
      financial statements. Actual results could differ from those estimates.

      Payment of Benefits--Benefit payments are recorded when paid.

3.    NON-PARTICIPANT DIRECTED NET ASSETS

      Effective October 1, 2005, the Plan was amended to allow participants to
      transfer funds from the Cinergy Common Stock Master Trust to other
      investments options at any time. Therefore, all investments became
      participant directed. Information about the net assets and the significant
      components of the changes in net assets relating to non-participant
      directed balances in 2004 is as follows:

                                                                December 31,
                                                                    2004

      Net assets--Cinergy Corp. Common Stock Master Trust        $87,968,163
                                                                 ===========


                                                                  Year Ended
                                                                 December 31,
                                                                      2004
      Changes in net assets:
           Employer contributions                                 $ 4,899,768
           Dividends                                                3,813,537
           Net appreciation                                         5,700,061
           Benefits paid to participants                           (1,901,921)
           Transfers to participant directed investments           (1,678,076)
           Interplan transfers                                     (1,059,027)
                                                               ----------------

                                                                   $ 9,774,342

4.    INVESTMENTS

      The Plan is a participant in the Cinergy Corp. Common Stock Master Trust,
      which was established by the Company for certain of the Plans' sponsor's
      defined contribution 401(k) plans. Cinergy Corp. also sponsors the
      following plans, whose investments are held in the Master Trust described
      above:

               The Cinergy Corp. Union Employees' 401(k) Plan, which covers
               union employees of Cinergy Corp.'s subsidiaries represented by
               the International Brotherhood of Electrical Workers, Local 1393.

               The Cinergy Corp. Non-Union Employees' 401(k) Plan, which covers
               non-union employees' of Cinergy Corp. and subsidiaries who
               meet minimum age requirements.

      The Plan has an undivided interest in the Master Trust. Fidelity
      Management Trust Company, in the name of U.S. Trust as Trustee, holds the
      Plan interest in Cinergy Corp. Common Stock Master Trust. A summary of the
      net assets of the Master Trust as of December 31 is as follows:

                                                   2005                 2004

         Cash and cash equivalents             $3,421,124         $  4,823,702
         Cinergy Corp. common stock           462,775,838          428,963,584
                                             ------------          -----------

                    Total investments         466,196,962          433,787,286

         Receivables:
           Accrued interest                        11,810                6,532
           Securities sold                      1,705,296               41,713
                                             ------------          -----------

                    Total assets              467,914,068          433,835,531

         Liabilities--Securities purchased      (109,812)             (64,030)
                                             ------------          -----------


         Net assets of Cinergy Corp.
         Common Stock Master Trust           $467,804,256         $433,771,501
                                             ==============       ============


      Allocation of the net assets of the Master Trust to participating plans as
      of December 31 is as follows:

                                        2005                      2004
                                       Amount    Percent     Amount    Percent

         Cinergy Corp. Union
           Employees' 401(k) Plan   $59,234,427    13 %  $ 56,024,465     13 %
         Cinergy Corp. Non-Union
           Employees' 401(k) Plan   215,588,648    46     198,406,071     46
         Cinergy Corp. Union Employees'
           Savings Incentive Plan   192,981,181    41     179,340,965     41
                                    -----------           -----------

                                   $467,804,256   100%   $433,771,501    100%
                                   ============          ============


        A summary of income of the Cinergy Corp. Common Stock Master Trust as of
        December 31 is as follows:

                                                     2005              2004

         Cinergy Corp. Common Stock Master Trust:
         Interest and dividends                   $20,468,016      $19,381,810
         Net appreciation in fair value of
         investments                               10,401,289       30,212,573
                                                  -----------       -----------

         Net Trust investment income              $30,869,305      $49,594,383
                                                  ===========      ===========


      The Plan's investments (excluding the Cinergy Corp. Common Stock Master
      Trust, which is detailed above), which includes gains and losses on
      investments bought and sold, as well as held during the year, appreciated
      in value as follows:

                                                      2005             2004

         Mutual funds                             $2,587,151       $5,379,801
         Common/collective trust                     128,170          181,386
                                                  ----------        ---------

         Net appreciation in fair value
         of investments                           $2,715,321       $5,561,187
                                                  ==========       ==========


      Allocations of income in Cinergy Corp. Common Stock Master Trust to
      participating plans as of December 31 are as follows:

                                            2005                   2004
                                       Amount    Percent     Amount     Percent

     Cinergy Corp. Union Employees'  $3,983,898    13 %   $ 6,427,198     13 %
       401(k) Plan
     Cinergy Corp. Non-Union Employees'
       401(k) Plan                   14,140,073    46      22,881,831     46
     Cinergy Corp. Union Employees'
       Savings Incentive Plan        12,745,334    41      20,285,354     41
                                     ----------            ----------

                                    $30,869,305   100%    $ 49,594,383   100%
                                   ============           ============


      The fair value of individual investments that represent 5% or more of the
      Plan's net assets available for benefits as of December 31 are as follows:

                                                    2005                2004

         *Plan interest in Cinergy Corp. Common
             Stock Master Trust                $192,981,181        $179,340,965
         *Fidelity Magellan Fund                 18,455,903          19,648,350
         *Fidelity Equity-Income Fund            20,778,673          20,917,025

         *Denotes party-in-interest.


5.    FEDERAL INCOME TAX STATUS

      The Internal Revenue Service has determined and informed the Plan by
      letter dated December 9, 2002, that the Plan and related trust are
      designed in accordance with applicable sections of the Internal Revenue
      Code ("IRC"). The Plan has been amended since receiving the determination
      letter. However, the Plan administrator believes that the Plan is designed
      and being operated in compliance with the applicable requirements of the
      IRC. Therefore, no provision for income taxes has been recorded in the
      accompanying financial statements.

6.    PLAN TERMINATION

      Although it has not expressed any intent to do so, the Company has the
      right under the Plan to discontinue its contributions at any time and to
      terminate the Plan subject to the provisions of ERISA. Any unvested
      amounts in the participant's account may be forfeited upon termination of
      the plan.

7.    RELATED PARTY TRANSACTIONS

      Certain Plan investments are shares of mutual funds managed by Fidelity.
      Fidelity is the Trustee for all of the Plan's investments, except the
      Cinergy Corp. Common Stock Master Trust, as defined by the Plan and
      therefore, these transactions qualify as party-in-interest transactions.
      US Trust is the Trustee of the Plan's interest in the Cinergy Corp. Common
      Stock Master Trust, which holds common stock of the Company as defined by
      the Plan and therefore, these transactions qualify as party-in-interest
      transactions.

8.    INVESTMENT RISK

      Investment securities, in general, are exposed to various risks, such as
      interest rate, credit and overall market volatility risks. Further, due to
      the level of risk associated with certain investment securities, it is
      reasonably possible that changes in the values of investment securities
      will occur in the near term and that such changes could materially affect
      the amounts reported in the accompanying statements of net assets
      available for benefits.

9.    PLAN CHANGES

      Effective January 1, 2005, the Plan was amended as follows:

         Clarified that an Eligible Employee did not include nonresident
         aliens with no United States source income,

         Provided that individuals who were terminated in connection with the
         transition of certain information technology-related responsibilities
         from the Company will be entitled to receive a profit-sharing
         contribution for 2004 even if they are not employed by the Company and
         its affiliates on December 31, 2004,

         Clarified the Plan's disability provisions,

         Reduced the amount to which an involuntary cash-out applies from
         $5,000 to $1,000 and provided that such determination shall be
         made after taking into account rollover contributions, and

         Clarified the Plan's ERISA Section 404(c) provisions.

      Effective October 1, 2005, the Plan was amended to allow employees to
      transfer funds out of the Cinergy Corp. Common Stock Master Trust to other
      investment options at any time.

      Effective January 1, 2006, the Plan was amended as follows:

         Clarified that it will no longer be a 401(k) safe harbor plan for
         plan years beginning after December 31, 2005

         Permitted eligible employees to make pre-tax and after-tax
         contributions from overtime pay, but without Cinergy matching
         those contributions

10.   SUBSEQUENT EVENT


      On April 3, 2006, the merger of Cinergy Corp. and Duke Energy was
      finalized. Shares of Cinergy common stock within the Plan were exchanged
      for shares of Duke Energy common stock. Effective April 3, 2006, the
      Cinergy Stock Fund was renamed the Duke Stock Fund.

                                     ******



                              SUPPLEMENTAL SCHEDULE




CINERGY CORP.
UNION EMPLOYEES' SAVINGS INCENTIVE PLAN

EIN: 31-1385023
PLAN NUMBER: 002

SCHEDULE H, PART IV, LINE 4i--SCHEDULE OF ASSETS (HELD AT END OF YEAR)
DECEMBER 31, 2005
- ---------------------------------------------------------------------------


 Identity of Issuer,      Description of Investment, Including
  Borrower, Lessor,       Maturity Date, Rate of Interest,             Current
  or Similar Party        Collateral, and Par or Maturity Value         Value

*Fidelity Investments     Magellan Fund                             $18,455,903
*Fidelity Investments     Equity Income Fund                         20,778,673
*Fidelity Investments     U.S. Bond Index Fund                        7,310,424
*Fidelity Investments     Diversified International Stock Fund        7,891,842
*Fidelity Investments     Low-Priced Stock Fund                      10,046,883
*Fidelity Investments     Freedom Income Fund                           698,770
*Fidelity Investments     Freedom 2000 Fund                             578,801
*Fidelity Investments     Freedom 2010 Fund                           2,574,341
*Fidelity Investments     Freedom 2020 Fund                           2,903,547
*Fidelity Investments     Freedom 2030 Fund                           1,710,644
*Fidelity Investments     Freedom 2040 Fund                             699,966
*Fidelity Investments     Blue Chip Fund                              5,253,205
 TCW Asset Management     TCW Galileo Value Opportunity Fund            751,554
 Rainier Investments      Rainier Small/Midcap I                      7,917,026

                                 Total investments in mutual funds   87,571,579
                                                                     ----------

*Cinergy Corp. Common Stock
  Master Trust           Plan interest in Master Trust              192,981,181
  JP Morgan Investments  JP Morgan Prime Money Market Instrument     12,063,763
*Fidelity Investments    Fidelity Managed Income Portfolio            1,483,759
*Fidelity Investments    US Equity Index Pool                         2,741,481
*Various Plan
  Participants           Participant Loans (interest rates
                         ranging from 6.25% to 7.75% and maturities
                         through July 2, 2010)                       11,929,541

*Denotes a party-in-interest.




                                   SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Plan
Committee has duly caused this annual report to be signed on its behalf by the
undersigned hereunto duly authorized.



                         CINERGY CORP. UNION EMPLOYEES'
                             SAVINGS INCENTIVE PLAN


                            By /s/ Darlene Glesenkamp

                               Plan Administrator



                                                                 EXHIBIT 23


CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM


We consent to the incorporation by reference in Registration Statement No.
333-72900 on Form S-8 of our report dated June 23, 2006, relating to the
financial statements of the Cinergy Corp. Union Employees' Savings Incentive
Plan appearing in this Annual Report on Form 11-K of the Cinergy Corp. Union
Employees' Savings Incentive Plan for the year ended December 31, 2005.


Cincinnati, Ohio
June 27, 2006