[FRONT OF CERTIFICATE]

EXHIBIT 4.1

[FRONT OF CERTIFICATE]

FULLY PAID AND NONASSESSABLE SHARES OF 7.50% SERIES F CUMULATIVE REDEEMABLE

PREFERRED STOCK, PAR VALUE $.01 PER SHARE, OF

CERTIFICATE OF STOCK

Kilroy Realty Corporation (the “Company”) transferable on the books of the Company by the holder hereof in person or by its duly authorized attorney, upon surrender of this Certificate properly endorsed. This Certificate and the shares represented hereby are issued and shall be held subject to all of the provisions of the charter of the Company (the “Charter”) and the Bylaws of the Company and any amendments thereto. This Certificate is not valid unless countersigned and registered by the Transfer Agent and Registrar.

In Witness Whereof, the Company has caused this Certificate to be executed on its behalf by its duly authorized officers.

Dated:

[BACK OF CERTIFICATE]

CLASSES OF STOCK

THE COMPANY IS AUTHORIZED TO ISSUE CAPITAL STOCK OF MORE THAN ONE CLASS, CONSISTING OF COMMON STOCK AND ONE OR MORE CLASSES OF PREFERRED STOCK, THE BOARD OF DIRECTORS IS AUTHORIZED TO DETERMINE THE PREFERENCES, LIMITATIONS AND RELATIVE RIGHTS OF ANY CLASS OF THE PREFERRED STOCK BEFORE THE ISSUANCE OF SHARES OF SUCH CLASS OF PREFERRED STOCK. THE COMPANY WILL FURNISH, WITHOUT CHARGE, TO ANY STOCKHOLDER MAKING A WRITTEN REQUEST THEREFOR, A COPY OF THE COMPANY’S CHARTER AND A WRITTEN STATEMENT OF THE DESIGNATIONS, RELATIVE RIGHTS, PREFERENCES, CONVERSION OR OTHER RIGHTS, VOTING POWERS, RESTRICTIONS, LIMITATIONS AS TO DIVIDENDS AND OTHER DISTRIBUTIONS, QUALIFICATIONS AND TERMS AND CONDITIONS OF REDEMPTION OF THE STOCK OF EACH CLASS WHICH THE COMPANY HAS THE AUTHORITY TO ISSUE AND, IF THE COMPANY IS AUTHORIZED TO ISSUE ANY PREFERRED OR SPECIAL CLASS AND SERIES, (i) THE DIFFERENCES IN THE RELATIVE RIGHTS AND PREFERENCES BETWEEN THE SHARES OF EACH SERIES TO THE EXTENT SET, AND (ii) THE AUTHORITY OF THE BOARD OF DIRECTORS TO SET SUCH RIGHTS AND PREFERENCES OF SUBSEQUENT SERIES, REQUESTS FOR SUCH WRITTEN STATEMENT MAY BE DIRECTED TO THE SECRETARY OF THE COMPANY AT ITS PRINCIPAL OFFICE.

RESTRICTION ON OWNERSHIP AND TRANSFER

THE SHARES OF SERIES F PREFERRED STOCK REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO RESTRICTIONS ON BENEFICIAL AND CONSTRUCTIVE OWNERSHIP AND TRANSFER FOR THE PURPOSE OF THE COMPANY’S MAINTENANCE OF ITS STATUS AS A REAL ESTATE INVESTMENT TRUST UNDER THE INTERNAL REVENUE CODE OF 1986, AS AMENDED (THE “CODE”). SUBJECT TO CERTAIN FURTHER RESTRICTIONS AND EXCEPT AS EXPRESSLY PROVIDED IN THE ARTICLES SUPPLEMENTARY FOR THE SERIES F PREFERRED STOCK, (i) NO PERSON MAY BENEFICIALLY OWN SHARES OF THE COMPANY’S SERIES F PREFERRED STOCK IN EXCESS OF 9.8% (BY VALUE OR BY NUMBER OF SHARES, WHICHEVER IS MORE RESTRICTIVE) OF THE OUTSTANDING SERIES F PREFERRED STOCK OF THE COMPANY; (ii) NO PERSON MAY CONSTRUCTIVELY OWN SHARES OF THE COMPANY’S SERIES F PREFERRED STOCK IN EXCESS OF 9.8% (BY VALUE OR BY NUMBER OF SHARES, WHICHEVER IS MORE RESTRICTIVE) OF THE OUTSTANDING SERIES F PREFERRED STOCK OF THE COMPANY; (iii) NO PERSON MAY BENEFICIALLY OR CONSTRUCTIVELY OWN SERIES F PREFERRED STOCK THAT, TAKING INTO ACCOUNT ANY OTHER CAPITAL STOCK OF THE COMPANY BENEFICIALLY OR CONSTRUCTIVELY OWNED BY SUCH PERSON, WOULD RESULT IN THE COMPANY BEING “CLOSELY HELD” UNDER SECTION 856(h) OF THE CODE OR OTHERWISE CAUSE THE COMPANY TO FAIL TO QUALIFY AS A REIT; AND (iv) NO PERSON MAY TRANSFER SERIES F PREFERRED STOCK IF SUCH TRANSFER WOULD RESULT IN THE CAPITAL STOCK OF THE COMPANY BEING OWNED BY FEWER THAN 100 PERSONS. ANY PERSON WHO BENEFICIALLY OR CONSTRUCTIVELY OWNS OR ATTEMPTS TO BENEFICIALLY OR CONSTRUCTIVELY OWN SERIES F PREFERRED STOCK WHICH CAUSES OR WILL CAUSE A PERSON TO BENEFICIALLY OR CONSTRUCTIVELY OWN SERIES F PREFERRED STOCK IN EXCESS OF THE ABOVE LIMITATIONS MUST IMMEDIATELY NOTIFY THE COMPANY. IF ANY OF THE RESTRICTIONS ON TRANSFER OR OWNERSHIP ARE VIOLATED, THE SERIES E PREFERRED STOCK REPRESENTED HEREBY IN EXCESS OF SUCH RESTRICTIONS WILL BE AUTOMATICALLY TRANSFERRED TO THE TRUSTEE OF A TRUST FOR THE BENEFIT OF ONE OR MORE CHARITABLE BENEFICIARIES. IN ADDITION, THE COMPANY MAY REDEEM SHARES UPON THE TERMS AND CONDITIONS SPECIFIED BY THE BOARD OF DIRECTORS IN ITS SOLE DISCRETION IF THE BOARD OF DIRECTORS DETERMINES THAT OWNERSHIP OR A TRANSFER OR OTHER EVENT MAY VIOLATE THE RESTRICTIONS DESCRIBED ABOVE. FURTHERMORE, UPON THE OCCURRENCE OF CERTAIN EVENTS, ATTEMPTED TRANSFERS IN VIOLATION OF THE RESTRICTIONS DESCRIBED ABOVE MAY BE VOID AB INITIO. ALL TERMS IN THIS LEGEND WHICH ARE DEFINED IN THE ARTICLES SUPPLEMENTARY FOR THE SERIES F PREFERRED STOCK SHALL HAVE THE MEANINGS ASCRIBED TO THEM IN SUCH ARTICLES SUPPLEMENTARY, AS THE SAME MAY BE AMENDED FROM TIME TO TIME, A COPY OF WHICH, INCLUDING THE RESTRICTIONS ON TRANSFER AND OWNERSHIP, WILL BE FURNISHED TO EACH HOLDER OF SERIES F PREFERRED STOCK ON REQUEST AND WITHOUT CHARGE. REQUESTS FOR SUCH A COPY MAY BE DIRECTED TO THE SECRETARY OF THE COMPANY AT ITS PRINCIPAL OFFICE.

The following abbreviations, when used in the inscription on the face of this certificate, shall be construed as though they were written out in full according to applicable laws or regulations:

Additional abbreviations may also be used though not in the above list.

FOR VALUE RECEIVED,                                      hereby sell, assign and transfer unto

(PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE OF ASSIGNEE)

                                                                                                                                                                                                                 Shares

of the Series F Preferred Stock represented by the within Certificate, and do hereby irrevocably constitute and appoint

                                                                                                                                                                                                            Attorney

to transfer the said stock on the books of the within named Company with full power of substitution in the premises,

Signature(s) Guaranteed