Exhibit 10.1

FIRST AMENDMENT TO REVOLVING

CREDIT AGREEMENT

THIS FIRST AMENDMENT TO REVOLVING CREDIT AGREEMENT (this “Amendment”) is made as
of June 22, 2011, by and among KILROY REALTY, L.P. (the “Borrower”), KILROY
REALTY CORPORATION (the “General Partner”), the BANKS listed on the signature
pages hereof, JPMORGAN CHASE BANK, N.A., as Administrative Agent for the Banks,
J.P. MORGAN SECURITIES LLC (successor to J.P. Morgan Securities Inc.) and
MERRILL LYNCH PIERCE FENNER & SMITH INCORPORATED (successor to Banc of America
Securities LLC), as Joint Lead Arrangers and Joint Bookrunners, BANK OF AMERICA,
N.A., as Syndication Agent, and THE BANK OF NOVA SCOTIA, PNC BANK, NATIONAL
ASSOCIATION, U.S. BANK NATIONAL ASSOCIATION, and BARCLAYS BANK PLC, as
Documentation Agents.

W I T N E S S E T H:

WHEREAS, the Borrower and the Banks have entered into the Revolving Credit
Agreement, as of August 10, 2010 (the “Credit Agreement”); and

WHEREAS, the parties desire to modify the Credit Agreement upon the terms and
conditions set forth herein.

NOW THEREFORE, for good and valuable consideration, the receipt and sufficiency
of which are hereby acknowledged, the parties do hereby agree as follows:

1. Definitions. All capitalized terms not otherwise defined herein shall have
the meanings ascribed to them in the Credit Agreement.

2. Amendments.

(a) All references to J.P. Morgan Securities Inc. shall be deemed to be to “J.P.
Morgan Securities LLC”, and all references to Banc of America Securities LLC
shall be deemed to be to “Merrill Lynch, Pierce, Fenner & Smith Incorporated”.

(b) The following definition shall be added in alphabetical order:

“First Amendment” means the First Amendment to Revolving Credit Agreement, dated
as of June 22, 2011, among the Borrower, the Administrative Agent and the Banks.

(c) The pricing table in the definition of “Applicable Margin” is hereby deleted
and the following substituted therefor:

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Range of Borrower’s Credit

Rating*

  

Applicable Margin for

Euro-Dollar Loans

(% per annum)

  

Applicable Margin for Base

Rate Loans

(% per annum)

<BBB-/Baa3 or unrated

   2.050%    1.050%

BBB-/Baa3

   1.750%    0.750%

BBB/Baa2

   1.450%    0.450%

BBB+/Baal

   1.250%    0.250%

A-/A3 or better

   1.175%    0.175%

(d) The definition of “Commitment” is hereby deleted and the following
substituted therefore:

“Commitment” means, with respect to each Bank, the amount indicated on its
signature page to the Amendment, as such amount may be reduced from time to time
pursuant to Sections 2.9(b) and 2.11(f), or increased pursuant to Section 9.17.

(e) The definition of “Extended Maturity Date” is hereby deleted and the
following substituted therefore: “‘Extended Maturity Date’ means August 10,
2016.”

(f) The reference to “7.75%” in the definition of FMV Cap Rate is hereby deleted
and “7.50%” substituted therefore.

(g) The definition of “Loan Documents” is hereby deleted and the following
substituted therefor:

“Loan Documents” means this Agreement, the First Amendment, the Notes, the
Guaranty, the Letter(s) of Credit, the Letter of Credit Documents and any
related documents.

(h) The definition of “Original Maturity Date” is hereby deleted and the
following substituted therefore: “‘Original Maturity Date’ means August 10,
2015.”

(i) The phrase “or land” appearing in clause (i) of the definition of
Unencumbered Asset Pool Properties, is hereby deleted.

(j) The phrase “land or” appearing in clauses (ii), (ii)(A) and (ii)(B) of the
definition of Unencumbered Asset Pool Properties Value, as well as the word
“land”, appearing in clause (ii)(B) thereof, are hereby deleted.

(k) The pricing table in Section 2.8(a) is hereby deleted and the following
substituted therefor:

 

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Borrower’s Credit Rating

  

Facility Fee

<BBB-/Baa3 or unrated

   .450%

BBB-/Baa3

   .350%

BBB/Baa2

   .300%

BBB+/Baal

   .250%

A-/A3 or better

   .225%

(l) The reference to “0.35%” in Section 2.8(d) is hereby deleted and “0.25%”
substituted therefor.

(m) The reference to “three (3) Euro-Dollar Business Days’” in Section 2.11(b)
is hereby deleted and the phrase “one (1) Euro-Dollar Business Day’s”
substituted therefor. In addition, the following is added to the second sentence
of Section 2.11(b), immediately before the period: “, and the Administrative
Agent shall notify the Banks of receipt of any such notice on the same
Euro-Dollar Business Day as received by it”

(n) The following is inserted to Section 5.8(a) immediately before the period:
“; provided, however, with respect to any period in which Borrower or any of its
Consolidated Subsidiaries have acquired a Real Property Asset (or multiple Real
Property Assets in a single transaction) for a price of more than $150,000,000,
Total Debt to Total Asset Value for such quarter and the next succeeding quarter
may increase to 65%, provided such ratio does not exceed 60% thereafter”

(o) Section 5.8(h) is hereby deleted.

(p) Section 8.3(a) is hereby amended by inserting the following after the last
sentence thereof:

For purposes hereof, all requests, rules, guidelines or directives in connection
with the Dodd-Frank Wall Street Reform and Consumer Protection Act shall be
deemed to be a change after the date hereof or after the date of the related
Money Market Quote, as applicable, regardless of the date enacted, adopted or
issued and all requests, rules, guidelines or directives promulgated by the Bank
for International Settlements, the Basel Committee on Banking Regulations and
Supervisory Practices (or any successor or similar authority) or the United
States financial regulatory authorities shall be deemed to be such a change
regardless of the date adopted, issued, promulgated or implemented, provided,
however, that if the applicable Bank shall have implemented changes prior to
Effective Date (as defined in the Amendment hereto) in response to any such
requests, rules, guidelines or directives, then the same shall not be deemed to
be a change after the date hereof or after the date of the related Money Market
Quote, as applicable, with respect to such Bank.

3. Effective Date. This Amendment shall become effective upon receipt by the
Administrative Agent of counterparts hereof signed by the Borrower and all the
Banks (the date of such receipt being deemed the “Effective Date”).

 

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4. Representations and Warranties. Borrower hereby represents and warrants that,
as of the Effective Date, (i) all the representations and warranties set forth
in the Credit Agreement, as amended hereby (other than representations and
warranties that expressly speak as of a different date), are true and complete
in all material respects, and (ii) no Default or Event of Default has occurred
or is outstanding.

5. Entire Agreement. This Amendment constitutes the entire and final agreement
among the parties hereto with respect to the subject matter hereof and there are
no other agreements, understandings, undertakings, representations or warranties
among the parties hereto with respect to the subject matter hereof except as set
forth herein.

6. Governing Law. This Amendment shall be governed by, and construed in
accordance with, the law of the State of New York.

7. Counterparts. This Amendment may be executed in any number of counterparts,
all of which taken together shall constitute one and the same agreement, and any
of the parties hereto may execute this Amendment by signing any such
counterpart.

8. Headings, Etc. Section or other headings contained in this Amendment are for
reference purposes only and shall not in any way affect the meaning or
interpretation of this Amendment.

9. No Further Modifications. All of the terms and conditions of the Credit
Agreement, as modified hereby, shall remain in full force and effect and, as
modified hereby, the Borrower confirms and ratifies all of the terms, covenants
and conditions of the Credit Agreement and the other Loan Documents in all
respects.

 

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IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be duly
executed as of the day and year first above written.

 

KILROY REALTY, L.P., a Delaware limited partnership By:  
Kilroy Realty Corporation, a Maryland corporation, its general partner By:  

/s/ Tyler H. Rose

Name:   Tyler H. Rose Title:   Executive Vice President and CFO By:  

/s/ Michelle Ngo

Name:   Michelle Ngo Title:   Vice President and Treasurer For purposes of being
bound by the amendments set forth herein, both as General Partner and as the
guarantor under the Guaranty: KILROY REALTY CORPORATION, a Maryland corporation,
By:  

/s/ Tyler H. Rose

Name:   Tyler H. Rose Title:   Executive Vice President and CFO By:  

/s/ Michelle Ngo

Name:   Michelle Ngo Title:   Vice President and Treasurer

 

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JPMORGAN CHASE BANK, N.A., as Administrative Agent and as a Bank By:  

/s/ Marc Costantino

Name:   Marc Costantino Title:   Executive Director

Commitment: $44,000,000

 

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BANK OF AMERICA, N.A., as Syndication Agent and as a Bank By:  

/s/ James P. Johnson

Name:   James P. Johnson Title:   Senior Vice President

Commitment: $44,000,000

 

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U.S. BANK NATIONAL ASSOCIATION, as

Documentation Agent and as a Bank

By:  

/s/ Patrick J. Brown

Name:   Patrick J. Brown Title:   Vice President

Commitment: $40,000,000

 

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PNC BANK, NATIONAL ASSOCIATION, as

Documentation Agent and as a Bank

By:  

/s/ Darin Mortimer

Name:   Darin Mortimer Title:   Vice President

Commitment: $40,000,000

 

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THE BANK OF NOVA SCOTIA, as Documentation Agent and as a Bank By:  

/s/ Christopher Usas

Name:   Christopher Usas Title:   Director

Commitment: $40,000,000

 

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BARCLAYS BANK PLC, as a Bank By:  

/s/ Michael Mozer

Name:   Michael Mozer Title:   Vice President

Commitment: $40,000,000

 

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BANK OF THE WEST, N.A., as a Bank By:  

/s/ Ben Arroyo

Name:   Ben Arroyo Title:   Vice President By:  

/s/ Arlene Mulchaey

Name:   Arlene Mulchaey Title:  

Assistant Vice President and

Documentation Supervisor

Commitment: $28,000,000

 

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COMPASS BANK, an Alabama banking
corporation, as a Bank By:  

/s/ Brian Tuerff

Name:   Brian Tuerff Title:   Senior Vice President

Commitment: $34,000,000

 

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SUMITOMO MITSUI BANKING

CORPORATION, as a Bank

By:  

/s/ William G. Karl

Name:   William G. Karl Title:   General Manager

Commitment: $28,000,000

 

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ROYAL BANK OF CANADA, as a Bank By:  

/s/ Dan LePage

Name:   Dan LePage Title:   Authorized Signatory

Commitment: $34,000,000

 

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UNION BANK, N.A., as a Bank By:  

/s/ Katherine Brandt

Name:   Katherine Brandt Title:   Vice President

Commitment: $34,000,000

 

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WELLS FARGO BANK, NATIONAL ASSOCIATION, as a Bank By:  

/s/ Mark Loewen

Name:   Mark Loewen Title:   Senior Vice President

Commitment: $30,000,000

 

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COMERICA BANK, as a Bank By:  

/s/ Charles Weddell

Name:   Charles Weddell Title:   Vice President

Commitment: $24,000,000

 

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KEYBANK, NATIONAL ASSOCIATION, as a Bank By:  

/s/ Timothy A. Sylvain

Name:   Timothy A. Sylvain Title:   AVP

Commitment: $20,000,000

 

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CATHAY UNITED BANK, LTD., as a Bank By:  

/s/ Grace Chou

Name:   Grace Chou Title:   SVP & General Manager

Commitment: $10,000,000

 

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CHANG HWA COMMERCIAL BANK,

LTD., LOS ANGELES BRANCH, as a Bank

By:  

/s/ Beverley Chen

Name:   Beverley Chen Title:   VP & General Manager

Commitment: $10,000,000

 

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