Exhibit 99.1

CommonWealth REIT Announces Results for the Periods

Ended June 30, 2010

Newton, MA (August 4, 2010): CommonWealth REIT (NYSE: CWH) today announced financial results for the quarter and six months ended June 30, 2010.

Results for the quarter ended June 30, 2010:

Funds from operations (FFO) available for common shareholders for the quarter ended June 30, 2010 was $60.2 million, or $0.93 per share basic and $0.92 per share diluted, compared to FFO available for common shareholders for the quarter ended June 30, 2009 of $63.9 million, or $1.14 per share basic and $1.11 per share diluted.

Net (loss) income available for common shareholders was $(2.7) million for the quarter ended June 30, 2010, compared to $46.9 million for the same quarter last year.  Net (loss) income available for common shareholders per share, basic and diluted, (EPS) for the quarters ended June 30, 2010 and 2009 was $(0.04) and $0.84, respectively.  Net loss for the quarter ended June 30, 2010 includes a loss of $21.5 million, or $0.33 per share, on asset impairment, partially offset by a gain of $11.5 million, or $0.18 per share, on sale of properties.  Net income for the quarter ended June 30, 2009 includes gains of $33.5 million, or $0.60 per share, from early extinguishment of debt and the sale of properties.

The weighted average number of basic and diluted common shares outstanding totaled 64,595,417 and 71,893,582, respectively, for the quarter ended June 30, 2010, and 55,924,176 and 63,222,340, respectively, for the quarter ended June 30, 2009.

A Maryland Real Estate Investment Trust with transferable shares of beneficial interest listed on the New York Stock Exchange.  No shareholder, Trustee or officer is personally liable for any act or obligation of the Trust.

On June 14, 2010, CWH’s board of trustees approved a reverse stock split that resulted in a one for four combination of CWH’s common shares of beneficial interest, $0.01 par value per share, effective July 1, 2010.  The reverse stock split reduced the number of CWH’s issued and outstanding common shares from 258,385,241 to 64,596,310.  The number of CWH’s authorized common shares did not change.  As required, common share amounts presented for all periods have been restated to reflect the reverse stock split.

A reconciliation of net income determined according to U.S. generally accepted accounting principles, or GAAP, to FFO for the quarters ended June 30, 2010 and 2009 appears later in this press release.

Results for the six months ended June 30, 2010:

FFO available for common shareholders for the six months ended June 30, 2010 was $120.2 million, or $1.98 per share basic and $1.95 per share diluted, compared to FFO available for common shareholders for the six months ended June 30, 2009 of $126.7 million, or $2.26 per share basic and $2.19 per share diluted.

Net income available for common shareholders was $22.0 million for the six months ended June 30, 2010, compared to $77.4 million for the same quarter last year.  Net income available for common shareholders per share, basic and diluted, (EPS) for the six months ended June 30, 2010 and 2009 was $0.36 and $1.38, respectively.  Net income for the six months ended June 30, 2010 includes gains of $27.9 million, or $0.46 per share, from the sale of properties and the issuance of shares by equity investee, partially offset by a loss of $21.5 million, or $0.35 per share, on asset impairment.  Net income for the six months ended June 30, 2009 includes gains of $49.7 million, or $0.89 per share, from early extinguishment of debt and the sale of properties.

The weighted average number of basic and diluted common shares outstanding totaled 60,685,295 and 67,983,460, respectively, for the six months ended June 30, 2010, and 56,163,198 and 63,461,362, respectively, for the six months ended June 30, 2009.

A reconciliation of net income determined according to U.S. GAAP to FFO for the six months ended June 30, 2010 and 2009 appears later in this press release.

Occupancy and Leasing Results (excluding properties classified in discontinued operations):

As of June 30, 2010, 86.0% of CWH’s total square feet was leased, compared to 86.6% as of March 31, 2010 and 89.1% as of June 30, 2009.

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CWH signed lease renewals for 968,000 square feet and new leases for 286,000 square feet during the quarter ended June 30, 2010 which had weighted average rental rates that were 6% below prior rents for the same space.  Average lease terms for leases signed during the second quarter of 2010 were 5.4 years.  Commitments for tenant improvement and leasing commission (TI/LC) costs for leases signed during the quarter ended June 30, 2010 totaled $9.99 per square foot on average.

Recent Investment and Sale Activities:

Since April 1, 2010, CWH has acquired eight properties and it has entered agreements to acquire 11 additional properties for an aggregate purchase price of approximately $359.6 million, excluding closing costs; CWH has also entered agreements to sell 15 properties for an aggregate sale price of $231.0 million, excluding closing costs:

·      In April 2010, CWH closed on the previously disclosed acquisition of an office property located in Denver, CO with 248,493 square feet.  This property is 100% leased to RE/MAX Realty as its corporate headquarters through April 2028.  The purchase price was $75.0 million, excluding closing costs.

·      In April 2010, CWH closed on the previously disclosed acquisition of an office property located in Colorado Springs, CO with 77,411 square feet.  The property is 100% leased to two tenants for a weighted (by rents) average lease term of approximately 4.7 years.  The purchase price was $10.8 million, excluding closing costs.

·      As previously disclosed, in May 2010, CWH entered an agreement to acquire MacarthurCook Industrial Property Fund, an Australian listed property trust with units publicly traded on the Australian Securities Exchange under the symbol “MIF”.  MIF currently owns 10 industrial properties with approximately 1.4 million square feet which are approximately 90% leased to 16 tenants for a weighted (by rents) average lease term of approximately five years.  Based on current exchange rates, the total consideration is estimated to be approximately $80.6 million, excluding closing costs, and closing is expected during the second half of 2010.  CWH’s acquisition of MIF is conditioned upon approval of MIF’s unitholders and other customary conditions, including certain conditions applicable to cross border transactions such as various tax rulings; accordingly, these conditions may not be satisfied, the required approvals may not be obtained and this transaction may not close.

·      In June 2010, CWH closed on the previously disclosed acquisition of two office properties located in Carson, CA with 212,000 square feet.  These properties are 100% leased to Northrop Grumman through 2016.  The purchase price was $27.9 million, excluding closing costs.

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·      In June 2010, CWH acquired two office properties located in Ann Arbor, MI with 410,410 square feet.  These properties are 88% leased to 16 tenants for a weighted (by rents) average lease term of approximately 7.6 years.  The purchase price was $65.2 million, excluding closing costs.

·      In July 2010, CWH acquired two office properties located in Stafford, VA with 117,949 square feet.  These properties are 90% leased to ten tenants for a weighted (by rents) average lease term of approximately 2.8 years.  The purchase price was $18.8 million, excluding closing costs.

·      In July 2010, CWH entered a purchase and sale agreement to acquire one office property located in Milwaukee, WI with 432,092 square feet.  This property is 94% leased to 29 tenants for a weighted (by rents) average lease term of 3.7 years.  The purchase price is $81.3 million, excluding closing costs.  CWH expects to acquire this property during the third quarter of 2010; however, this acquisition is subject to customary closing conditions and no assurance can be given that this acquisition will be consummated in that time period or at all.

·      As previously disclosed, in June 2010, CWH entered agreements with Government Properties Income Trust to sell 15 properties majority leased to the U.S. Government with approximately 1.9 million square feet for an aggregate sale price of $231.0 million, excluding closing costs.  In June and July 2010, CWH sold eight of these properties with 747,658 square feet for an aggregate sale price of $88.7 million, excluding closing costs.  The remaining seven properties with 1,124,206 square feet are subject to purchase and sale agreements for an aggregate sale price of $142.3 million, excluding closing costs.  The remaining sales are expected to close prior to March 31, 2011 and are subject to various contractual contingencies typical of large commercial property transactions; accordingly, CWH can provide no assurances that it will sell these properties.

Conference Call:

On Wednesday, August 4, 2010, at 1:00 p.m. Eastern Time, Adam Portnoy, Managing Trustee, and John Popeo, Chief Financial Officer, will host a conference call to discuss the second quarter financial results.  Following the company’s remarks, there will be a short question and answer period.

The conference call telephone number is (888) 690-2876.  Participants calling from outside the United States and Canada should dial (913) 312-1456.  No pass code is necessary to access either call.  Participants should dial in about 15 minutes prior to the scheduled start of the call.  A replay of the conference call will be available through 4:00 p.m. Eastern Time on Wednesday, August 11, 2010.  To hear the replay, dial (719) 457-0820.  The replay pass code is 5349074.

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A live audio webcast of the conference call will also be available in a listen only mode on CWH’s website, which is located at www.cwhreit.com.  Participants wanting to access the webcast should visit CWH’s website about five minutes before the call.  The archived webcast will be available for replay on CWH’s website for about one week after the call.  The recording and retransmission in any way of CWH’s second quarter conference call is strictly prohibited without the prior written consent of CWH.

Supplemental Data:

A copy of CWH’s Second Quarter 2010 Supplemental Operating and Financial Data is available for download at CWH’s website, www.cwhreit.com.

CommonWealth REIT is a real estate investment trust, or REIT, which primarily owns office and industrial properties located throughout the United States.  As of June 30, 2010, CWH owned 521 properties with 67.5 million square feet, including 17.9 million square feet of leased industrial and commercial lands in Oahu, Hawaii.  CWH is headquartered in Newton, Massachusetts.

Please see the pages attached hereto for a more detailed statement of our operating results and financial condition and for an explanation of our calculation of FFO.  CWH’s website is not incorporated as part of this press release.

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WARNING CONCERNING FORWARD LOOKING STATEMENTS

THIS PRESS RELEASE CONTAINS STATEMENTS WHICH CONSTITUTE FORWARD LOOKING STATEMENTS WITHIN THE MEANING OF THE PRIVATE SECURITIES LITIGATION REFORM ACT OF 1995 AND OTHER FEDERAL SECURITIES LAWS.  ALSO, WHENEVER WE USE WORDS SUCH AS “BELIEVE”, “EXPECT”, “ANTICIPATE”, “INTEND”, “PLAN”, “ESTIMATE”, OR SIMILAR EXPRESSIONS, WE ARE MAKING FORWARD LOOKING STATEMENTS.  THESE FORWARD LOOKING STATEMENTS AND THEIR IMPLICATIONS ARE BASED UPON OUR PRESENT INTENT, BELIEFS OR EXPECTATIONS, BUT FORWARD LOOKING STATEMENTS AND THEIR IMPLICATIONS ARE NOT GUARANTEED TO OCCUR AND MAY NOT OCCUR. OUR ACTUAL RESULTS MAY DIFFER MATERIALLY FROM THOSE CONTAINED IN OR IMPLIED BY OUR FORWARD LOOKING STATEMENTS AS A RESULT OF VARIOUS FACTORS. FOR EXAMPLE:

·      THIS PRESS RELEASE STATES THAT WE HAVE ENTERED INTO AGREEMENTS TO ACQUIRE AND SELL PROPERTIES.  THESE AGREEMENTS ARE SUBJECT TO VARIOUS TERMS AND CONDITIONS.  THESE TERMS AND CONDITIONS MAY NOT BE MET.  AS A RESULT, SOME OR ALL OF THESE TRANSACTIONS MAY NOT OCCUR OR MAY BE DELAYED.

OTHER IMPORTANT FACTORS THAT COULD CAUSE ACTUAL RESULTS TO DIFFER MATERIALLY FROM THOSE IN OR IMPLIED BY OUR FORWARD LOOKING STATEMENTS ARE DESCRIBED MORE FULLY UNDER “RISK FACTORS” IN OUR ANNUAL REPORT ON FORM 10-K FOR THE YEAR ENDED DECEMBER 31, 2009.

YOU SHOULD NOT PLACE UNDUE RELIANCE UPON FORWARD LOOKING STATEMENTS.

EXCEPT AS REQUIRED BY LAW, WE DO NOT INTEND TO UPDATE OR CHANGE ANY FORWARD LOOKING STATEMENTS AS A RESULT OF NEW INFORMATION, FUTURE EVENTS OR OTHERWISE.

(END)

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CommonWealth REIT

Consolidated Statements of Income and Funds from Operations

(amounts in thousands, except per share data)

(unaudited)

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CommonWealth REIT

Consolidated Statements of Income and Funds from Operations (continued)

(amounts in thousands, except per share data)

(unaudited)

(1)   Represents the closing costs associated with acquisitions that are expensed pursuant to the Business Combinations Topic of the FASB Accounting Standards CodificationTM.

(2)   We compute FFO as shown in the calculation above.  Our calculation of FFO differs from the National Association of Real Estate Investment Trusts, or NAREIT, definition because we exclude acquisition costs as described in Note 1 above, gains from equity investments, gain on early extinguishment of debt, loss on early extinguishment of debt unless settled in cash, and loss on asset impairment.  We consider FFO to be an appropriate measure of performance for a REIT, along with net income and cash flow from operating, investing and financing activities.  We believe that FFO provides useful information to investors because, by excluding the effects of certain historical amounts, such as depreciation expense and items referred to above, FFO can facilitate a comparison of operating performance between periods and among REITs.  FFO does not represent cash generated by operating activities in accordance with U.S. generally accepted accounting principles, or GAAP, and should not be considered an alternative to net income or cash flow from operating activities as a measure of financial performance or liquidity.  Also, some REITs may calculate FFO differently than us.

(3)   As of June 30, 2010, our 15,180 outstanding series D preferred shares were convertible into 7,298 common shares.  The effect of a conversion of our series D convertible preferred shares on income from continuing operations available for common shareholders per share is anti-dilutive to income, but dilutive to FFO for the quarters and six months ended June 30, 2010 and 2009.  Set forth below is the calculation of diluted net income available for common shareholders, diluted FFO available for common shareholders and diluted weighted average common shares outstanding.

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CommonWealth REIT

Consolidated Balance Sheets

(amounts in thousands, except share data)

(unaudited)

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