UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

FORM N-Q

QUARTERLY SCHEDULE OF PORTFOLIO HOLDINGS OF REGISTERED MANAGEMENT INVESTMENT COMPANY

Investment Company Act file number 811-6081

Nuveen California Municipal Market Opportunity Fund, Inc.

(Exact name of registrant as specified in charter)

Nuveen Investments

        333 West Wacker Drive, Chicago, Illinois 60606         

(Address of principal executive offices) (Zip code)

Kevin J. McCarthy

Vice President and Secretary

        333 West Wacker Drive, Chicago, Illinois 60606         

(Name and address of agent for service)

Registrant's telephone number, including area code:         312-917-7700        

Date of fiscal year end:            2/28          

Date of reporting period:         5/31/10         

Form N-Q is to be used by management investment companies, other than small business investment companies registered on Form N-5 (§§ 239.24 and 274.5 of this chapter), to file reports with the Commission, not later than 60 days after the close of the first and third fiscal quarters, pursuant to rule 30b1-5 under the Investment Company Act of 1940 (17 CFR 270.30b1-5). The Commission may use the information provided on Form N-Q in its regulatory, disclosure review, inspection, and policymaking roles.

A registrant is required to disclose the information specified by Form N-Q, and the Commission will make this information public. A registrant is not required to respond to the collection of information contained in Form N-Q unless the Form displays a currently valid Office of Management and Budget ("OMB") control number. Please direct comments concerning the accuracy of the information collection burden estimate and any suggestions for reducing the burden to the Secretary, Securities and Exchange Commission, 450 Fifth Street, NW, Washington, DC 20549-0609. The OMB has reviewed this collection of information under the clearance requirements of 44 U.S.C. § 3507.

Item 1. Schedule of Investments

	Portfolio of Investments (Unaudited)
	Nuveen California Municipal Market Opportunity Fund, Inc. (NCO)
	May 31, 2010
Principal		Optional Call
Amount (000)	Description (1)	Provisions (2)	Ratings (3)	Value
	Consumer Staples – 6.0% (4.2% of Total Investments)
$      330	California County Tobacco Securitization Agency, Tobacco Settlement Asset-Backed Bonds, Sonoma	6/15 at 100.00	BBB	$      311,807
	County Tobacco Securitization Corporation, Series 2005, 4.250%, 6/01/21
2,000	Golden State Tobacco Securitization Corporation, California, Tobacco Settlement Asset-Backed	6/17 at 100.00	BBB	1,466,540
	Bonds, Series 2007A-1, 5.750%, 6/01/47
8,090	Golden State Tobacco Securitization Corporation, California, Tobacco Settlement Asset-Backed	6/22 at 100.00	BBB	5,189,250
	Bonds, Series 2007A-2, 0.000%, 6/01/37
10,420	Total Consumer Staples			6,967,597
	Education and Civic Organizations – 5.7% (4.0% of Total Investments)
100	California Educational Facilities Authority, Revenue Bonds, University of Redlands, Series	10/15 at 100.00	A3	96,920
	2005A, 5.000%, 10/01/35
	California Educational Facilities Authority, Revenue Bonds, University of the Pacific, Series 2006:
70	5.000%, 11/01/21	11/15 at 100.00	A2	73,531
95	5.000%, 11/01/25	11/15 at 100.00	A2	97,352
1,000	California Infrastructure Economic Development Bond Bank, Revenue Bonds, Scripps Research	7/15 at 100.00	Aa3	1,056,940
	Institute, Series 2005A, 5.000%, 7/01/24
1,680	California State Public Works Board, Lease Revenue Bonds, University of California Regents,	3/18 at 100.00	Aa2	1,742,479
	Tender Option Bond Trust 1065, 9.041%, 3/01/33 (IF)
2,000	Long Beach Bond Financing Authority, California, Lease Revenue Refunding Bonds, Long Beach	11/11 at 101.00	BBB	1,887,500
	Aquarium of the South Pacific, Series 2001, 5.250%, 11/01/30 – AMBAC Insured
2,000	San Diego County, California, Certificates of Participation, Burnham Institute, Series 2006,	9/15 at 102.00	Baa3	1,741,320
	5.000%, 9/01/34
6,945	Total Education and Civic Organizations			6,696,042
	Health Care – 24.2% (16.9% of Total Investments)
5,260	California Health Facilities Financing Authority, Revenue Bonds, Childrens Hospital Los	7/20 at 100.00	AAA	5,271,993
	Angeles, Series 2010A, 5.250%, 7/01/38 – AGC Insured
240	California Health Facilities Financing Authority, Revenue Bonds, Kaiser Permanante System,	4/16 at 100.00	A+	232,068
	Series 2006, 5.000%, 4/01/37
5,305	California Health Facilities Financing Authority, Revenue Bonds, Sutter Health, Series 2007A,	11/16 at 100.00	Aa3	5,284,364
	5.250%, 11/15/46 (UB)
3,200	California Infrastructure Economic Development Bank, Revenue Bonds, Kaiser Hospital Assistance	8/11 at 102.00	A+	3,240,544
	LLC, Series 2001A, 5.550%, 8/01/31
1,060	California Municipal Financing Authority, Certificates of Participation, Community Hospitals	2/17 at 100.00	Baa2	930,754
	of Central California, Series 2007, 5.250%, 2/01/46
569	California Statewide Communities Development Authority, Revenue Bonds, Saint Joseph Health	7/18 at 100.00	AAA	615,943
	System, Trust 2554, 18.449%, 7/01/47 – AGM Insured (IF)
1,000	California Statewide Community Development Authority, Insured Health Facility Revenue Bonds,	10/17 at 100.00	A–	917,760
	Henry Mayo Newhall Memorial Hospital, Series 2007A, 5.000%, 10/01/37
1,500	California Statewide Community Development Authority, Revenue Bonds, Daughters of Charity	7/15 at 100.00	BBB	1,432,335
	Health System, Series 2005A, 5.250%, 7/01/24
755	California Statewide Community Development Authority, Revenue Bonds, Kaiser Permanante System,	3/16 at 100.00	A+	719,651
	Series 2006, 5.000%, 3/01/41
135	California Statewide Community Development Authority, Revenue Bonds, Kaiser Permanente System,	8/16 at 100.00	A+	135,980
	Series 2001C, 5.250%, 8/01/31
675	California Statewide Community Development Authority, Revenue Bonds, Sherman Oaks Health	No Opt. Call	A1	679,982
	System, Series 1998A, 5.000%, 8/01/22 – AMBAC Insured
2,585	California Statewide Community Development Authority, Revenue Bonds, Sutter Health, Series	11/15 at 100.00	Aa3	2,495,430
	2005A, 5.000%, 11/15/43
1,000	Loma Linda, California, Hospital Revenue Bonds, Loma Linda University Medical Center, Series	12/15 at 100.00	BBB	965,700
	2005A, 5.000%, 12/01/23
1,150	Loma Linda, California, Hospital Revenue Bonds, Loma Linda University Medical Center, Series	12/17 at 100.00	BBB	1,298,649
	2008A, 8.250%, 12/01/38
2,205	Madera County, California, Certificates of Participation, Children’s Hospital Central	3/20 at 100.00	A–	2,167,052
	California, Series 2010, 5.375%, 3/15/36
1,000	Rancho Mirage Joint Powers Financing Authority, California, Revenue Bonds, Eisenhower Medical	7/17 at 100.00	A3	927,490
	Center, Series 2007A, 5.000%, 7/01/38
1,000	The Regents of the University of California, Medical Center Pooled Revenue Bonds, Series	5/15 at 101.00	Aa2	953,420
	2007A, 4.500%, 5/15/37 – NPFG Insured
28,639	Total Health Care			28,269,115
	Housing/Single Family – 0.2% (0.1% of Total Investments)
195	California Housing Finance Agency, Home Mortgage Revenue Bonds, Series 2006H, 5.750%, 8/01/30 –	2/16 at 100.00	A	199,409
	FGIC Insured (Alternative Minimum Tax)
	Industrials – 0.6% (0.4% of Total Investments)
750	California Pollution Control Financing Authority, Solid Waste Disposal Revenue Bonds, Waste	1/16 at 102.00	BBB	754,913
	Management Inc., Series 2002A, 5.000%, 1/01/22 (Alternative Minimum Tax)
	Long-Term Care – 2.1% (1.5% of Total Investments)
2,900	California Statewide Communities Development Authority, Revenue Bonds, Inland Regional Center	12/17 at 100.00	Baa1	2,446,585
	Project, Series 2007, 5.250%, 12/01/27
	Tax Obligation/General – 18.7% (13.1% of Total Investments)
4,125	Alameda Unified School District, Alameda County, California, General Obligation Bonds, Series	No Opt. Call	AAA	1,765,830
	2004A, 0.000%, 8/01/25 – AGM Insured
2,000	California, General Obligation Bonds, Various Purpose Series 2009, 6.000%, 11/01/39	11/19 at 100.00	A1	2,192,860
1,350	Coachella Valley Unified School District, Riverside County, California, General Obligation	8/15 at 100.00	A1	1,360,922
	Bonds, Series 2005A, 5.000%, 8/01/30 – FGIC Insured
2,150	Los Rios Community College District, Sacramento, El Dorado and Yolo Counties, California,	8/14 at 102.00	AAA	2,363,839
	General Obligation Bonds, Series 2006C, 5.000%, 8/01/24 – AGM Insured (UB)
4,100	Monrovia Unified School District, Los Angeles County, California, General Obligation Bonds,	No Opt. Call	Aa3	1,490,309
	Series 2001B, 0.000%, 8/01/27 – FGIC Insured
2,500	Oakland Unified School District, Alameda County, California, General Obligation Bonds, Series	8/12 at 100.00	A1	2,581,350
	2002, 5.250%, 8/01/21 – FGIC Insured
1,000	Pomona Unified School District, Los Angeles County, California, General Obligation Refunding	8/11 at 103.00	A	1,092,230
	Bonds, Series 1997A, 6.150%, 8/01/15 – NPFG Insured
25	Riverside Community College District, California, General Obligation Bonds, Series 2004A,	8/14 at 100.00	Aa2	27,531
	5.250%, 8/01/24 – NPFG Insured
210	Roseville Joint Union High School District, Placer County, California, General Obligation	8/15 at 100.00	AA–	217,730
	Bonds, Series 2006B, 5.000%, 8/01/27 – FGIC Insured
5,000	San Diego Unified School District, California, General Obligation Bonds, Election of 1998,	7/10 at 100.00	Aa1	5,019,150
	Series 2000B, 5.125%, 7/01/21 – NPFG Insured
4,970	San Rafael City High School District, Marin County, California, General Obligation Bonds,	No Opt. Call	AA	1,874,088
	Series 2004B, 0.000%, 8/01/27 – FGIC Insured
4,175	Southwestern Community College District, San Diego County, California, General Obligation	No Opt. Call	Aa2	1,786,441
	Bonds, Series 2004, 0.000%, 8/01/25 – FGIC Insured
31,605	Total Tax Obligation/General			21,772,280
	Tax Obligation/Limited – 24.5% (17.1% of Total Investments)
2,000	California State Public Works Board, Lease Revenue Bonds, Department of Mental Health,	6/14 at 100.00	A2	2,082,940
	Coalinga State Hospital, Series 2004A, 5.500%, 6/01/19
260	Capistrano Unified School District, Orange County, California, Special Tax Bonds, Community	9/15 at 100.00	A	254,023
	Facilities District, Series 2005, 5.000%, 9/01/24 – FGIC Insured
770	Chino Redevelopment Agency, California, Merged Chino Redevelopment Project Area Tax Allocation	9/16 at 101.00	A–	684,830
	Bonds, Series 2006, 5.000%, 9/01/38 – AMBAC Insured
1,035	Hawthorne Community Redevelopment Agency, California, Project Area 2 Tax Allocation Bonds,	9/16 at 100.00	A–	961,256
	Series 2006, 5.250%, 9/01/36 – SYNCORA GTY Insured
	Irvine, California, Unified School District, Community Facilities District Special Tax Bonds,
	Series 2006A:
120	5.000%, 9/01/26	9/16 at 100.00	N/R	109,853
275	5.125%, 9/01/36	9/16 at 100.00	N/R	238,161
470	Los Angeles Community Redevelopment Agency, California, Lease Revenue Bonds, Manchester Social	9/15 at 100.00	A1	419,362
	Services Project, Series 2005, 5.000%, 9/01/37 – AMBAC Insured
	Modesto Schools Infrastructure Financing Agency, Stanislaus County, California, Special Tax
	Revenue Bonds, Series 2004:
1,375	5.250%, 9/01/25 – AMBAC Insured	9/14 at 100.00	N/R	1,291,029
1,500	5.250%, 9/01/26 – AMBAC Insured	9/14 at 100.00	N/R	1,395,840
10,900	Ontario Redevelopment Financing Authority, San Bernardino County, California, Revenue	No Opt. Call	A	12,700,898
	Refunding Bonds, Redevelopment Project 1, Series 1995, 7.400%, 8/01/25 – NPFG Insured
1,000	Ontario, California, Special Tax Bonds, Community Facilities District 5, Freeway Interchange	9/10 at 100.00	N/R	1,004,190
	Project, Series 1997, 6.375%, 9/01/17
1,065	Panama-Buena Vista Union School District, California, Certificates of Participation, School	9/16 at 100.00	A1	1,119,773
	Construction Project, Series 2006, 5.000%, 9/01/22 – NPFG Insured
225	Rialto Redevelopment Agency, California, Tax Allocation Bonds, Merged Project Area, Series	9/15 at 100.00	A–	202,367
	2005A, 5.000%, 9/01/35 – SYNCORA GTY Insured
1,440	Riverside County Redevelopment Agency, California, Tax Allocation Housing Bonds, Series 2010A,	10/20 at 100.00	A2	1,462,032
	6.000%, 10/01/39 (WI/DD, Settling 6/03/10)
280	Roseville, California, Certificates of Participation, Public Facilities, Series 2003A, 5.000%,	8/13 at 100.00	AA–	280,549
	8/01/25 – AMBAC Insured
2,500	Sacramento City Financing Authority, California, Lease Revenue Refunding Bonds, Series 1993A,	No Opt. Call	A1	2,678,825
	5.400%, 11/01/20 – AMBAC Insured
1,200	San Jose Financing Authority, California, Lease Revenue Refunding Bonds, Convention Center	9/11 at 100.00	AA+	1,252,284
	Project, Series 2001F, 5.000%, 9/01/20 – NPFG Insured
485	San Mateo Union High School District, San Mateo County, California, Certificates of	12/17 at 100.00	AA–	455,924
	Participation, Phase 1, Series 2007A, 5.000%, 12/15/30 – AMBAC Insured
26,900	Total Tax Obligation/Limited			28,594,136
	Transportation – 11.4% (8.0% of Total Investments)
1,355	Bay Area Toll Authority, California, Revenue Bonds, San Francisco Bay Area Toll Bridge, Series	4/18 at 100.00	AA	1,595,106
	2008, Trust 3211, 13.261%, 4/01/39 (IF)
4,000	Foothill/Eastern Transportation Corridor Agency, California, Toll Road Revenue Refunding	1/14 at 101.00	BBB–	4,029,160
	Bonds, Series 1999, 5.875%, 1/15/29
5,210	Port of Oakland, California, Revenue Bonds, Series 2000K, 5.750%, 11/01/29 – FGIC Insured	11/10 at 100.00	A	5,210,521
2,465	San Francisco Airports Commission, California, Special Facilities Lease Revenue Bonds, San	7/10 at 100.00	AAA	2,467,465
	Francisco International Airport, SFO Fuel Company LLC, Series 2000A, 6.125%, 1/01/27 – AGM
	Insured (Alternative Minimum Tax)
13,030	Total Transportation			13,302,252
	U.S. Guaranteed – 19.7% (13.8% of Total Investments) (4)
3,000	California Department of Water Resources, Power Supply Revenue Bonds, Series 2002A, 5.125%,	5/12 at 101.00	Aaa	3,290,160
	5/01/18 (Pre-refunded 5/01/12)
25	California Department of Water Resources, Water System Revenue Bonds, Central Valley Project,	12/11 at 100.00	AAA	26,882
	Series 2001W, 5.500%, 12/01/15 (Pre-refunded 12/01/11)
10	California Department of Water Resources, Water System Revenue Bonds, Central Valley Project,	No Opt. Call	AAA	12,131
	Series 2002X, 5.500%, 12/01/17 – FGIC Insured (ETM)
2,100	California, General Obligation Bonds, Series 2004, 5.250%, 4/01/34 (Pre-refunded 4/01/14)	4/14 at 100.00	AAA	2,420,061
1,475	Golden State Tobacco Securitization Corporation, California, Tobacco Settlement Asset-Backed	6/13 at 100.00	AAA	1,644,227
	Bonds, Series 2003A-1, 6.250%, 6/01/33 (Pre-refunded 6/01/13)
5,000	Los Angeles Unified School District, California, General Obligation Bonds, Series 2000D,	7/10 at 100.00	Aa2 (4)	5,023,350
	5.375%, 7/01/25 (Pre-refunded 7/01/10) – FGIC Insured
2,000	Monterey County, California, Certificates of Participation, Master Plan Financing, Series 2001,	8/11 at 100.00	AA– (4)	2,104,280
	5.000%, 8/01/21 (Pre-refunded 8/01/11) – NPFG Insured
875	Orange County Water District, California, Revenue Certificates of Participation, Series 2003B,	8/13 at 100.00	AAA	978,696
	5.000%, 8/15/34 – NPFG Insured (ETM)
4,000	Pomona, California, GNMA/FHLMC Collateralized Single Family Mortgage Revenue Refunding Bonds,	No Opt. Call	AAA	5,265,480
	Series 1990B, 7.500%, 8/01/23 (ETM)
1,875	Riverside Community College District, California, General Obligation Bonds, Series 2004A,	8/14 at 100.00	AA– (4)	2,175,900
	5.250%, 8/01/24 (Pre-refunded 8/01/14) – NPFG Insured
20,360	Total U.S. Guaranteed			22,941,167
	Utilities – 6.4% (4.5% of Total Investments)
1,500	California Pollution Control Financing Authority, Revenue Refunding Bonds, Southern California	9/10 at 100.50	A	1,513,650
	Edison Company, Series 1999A, 5.450%, 9/01/29 – NPFG Insured
2,815	California Statewide Community Development Authority, Certificates of Participation Refunding,	6/10 at 100.00	N/R	2,601,989
	Rio Bravo Fresno Project, Series 1999A, 6.500%, 12/01/18 (5)
1,365	Long Beach Bond Finance Authority, California, Natural Gas Purchase Revenue Bonds, Series	No Opt. Call	A	1,340,307
	2007A, 5.500%, 11/15/37
455	Merced Irrigation District, California, Electric System Revenue Bonds, Series 2005, 5.125%,	9/15 at 100.00	N/R	424,019
	9/01/31 – SYNCORA GTY Insured
1,500	Southern California Public Power Authority, California, Milford Wind Corridor Phase I Revenue	No Opt. Call	AA–	1,567,350
	Bonds, Series 2010-1, 5.000%, 7/01/28
7,635	Total Utilities			7,447,315
	Water and Sewer – 23.4% (16.4% of Total Investments)
1,020	California Department of Water Resources, Water System Revenue Bonds, Central Valley Project,	No Opt. Call	AAA	1,234,975
	Series 2002X, 5.500%, 12/01/17 – FGIC Insured
2,500	El Centro Financing Authority, California, Water Revenue Bonds, Series 2006A, 4.750%, 10/01/31 –	10/16 at 100.00	AAA	2,450,550
	AGM Insured
750	Fortuna Public Finance Authority, California, Water Revenue Bonds, Series 2006, 5.000%,	10/16 at 100.00	AAA	753,593
	10/01/36 – AGM Insured
3,380	Orange County Sanitation District, California, Certificates of Participation, Trust 11738,	2/19 at 100.00	AAA	4,153,750
	Series 2009, 17.573%, 2/01/35 (IF)
3,500	Placerville Public Financing Authority, California, Wastewater System Refinancing and	9/16 at 100.00	N/R	3,162,810
	Improvement Project Revenue Bonds, Series 2006, 5.000%, 9/01/34 – SYNCORA GTY Insured
350	Sacramento County Sanitation District Financing Authority, California, Revenue Bonds, Series	6/16 at 100.00	AA	360,608
	2006, 5.000%, 12/01/31 – FGIC Insured
2,630	San Diego Public Facilities Financing Authority, California, Sewerage Revenue Bonds, Refunding	5/20 at 100.00	Aa3	2,888,870
	Series 2010A, 5.250%, 5/15/27
2,000	San Francisco City and County Public Utilities Commission, California, Clean Water Revenue	4/13 at 100.00	AA–	2,168,819
	Refunding Bonds, Series 2003A, 5.250%, 10/01/20 – NPFG Insured
10,000	Santa Maria, California, Subordinate Water and Wastewater Revenue Certificates of	8/12 at 101.00	N/R	10,182,299
	Participation, Series 1997A, 5.550%, 8/01/27 – AMBAC Insured
26,130	Total Water and Sewer			27,356,274
$      175,509	Total Investments (cost $164,648,633) – 142.9%			166,747,085
	Floating Rate Obligations – (3.7)%			(4,285,000)
	Other Assets Less Liabilities – 3.5%			4,050,640
	Variable Rate Demand Preferred Shares, at Liquidation Value – (42.7)% (6)			(49,800,000)
	Net Assets Applicable to Common Shares – 100%			$ 116,712,725

Fair Value Measurements

In determining the value of the Fund's investments, various inputs are used. These inputs are summarized in the three broad levels listed below:

  Level 1 – Quoted prices in active markets for identical securities.

  Level 2 – Other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risk, etc.).

  Level 3 – Significant unobservable inputs (including management's assumptions in determining the fair value of investments).

The inputs or methodologies used for valuing securities are not an indication of the risk associated with investing in those securities. The following is a summary of the Fund's fair value measurements as of May 31, 2010:

	Level 1	Level 2	Level 3	Total
Investments:
Municipal Bonds	$ —	$166,747,085	$ —	$166,747,085

Income Tax Information

The following information is presented on an income tax basis. Differences between amounts for financial statement and federal income tax purposes are primarily due to timing differences in recognizing taxable market discount, timing differences in recognizing certain gains and losses on investment transactions and the treatment of investments in inverse floating rate securities reflected as financing transactions, if any. To the extent that differences arise that are permanent in nature, such amounts are reclassified within the capital accounts on the Statement of Assets and Liabilities presented in the annual report, based on their federal tax basis treatment; temporary differences do not require reclassification. Temporary and permanent differences do not impact the net asset value of the Fund.

At May 31, 2010, the cost of investments was $160,310,541.

Gross unrealized appreciation and gross unrealized depreciation of investments at May 31, 2010, were as follows:

Gross unrealized:
Appreciation	$ 7,409,004
Depreciation	(5,257,402)
Net unrealized appreciation (depreciation) of investments	$ 2,151,602

(1)	All percentages shown in the Portfolio of Investments are based on net assets applicable to Common
	shares unless otherwise noted.
(2)	Optional Call Provisions: Dates (month and year) and prices of the earliest optional call or redemption.
	There may be other call provisions at varying prices at later dates. Certain mortgage-backed securities
	may be subject to periodic principal paydowns.
(3)	Ratings: Using the highest of Standard & Poor’s Group ("Standard & Poor's"), Moody’s Investor Service, Inc.
	("Moody's") or Fitch, Inc. ("Fitch") rating. Ratings below BBB by Standard & Poor’s, Baa by Moody’s or
	BBB by Fitch are considered to be below investment grade.
(4)	Backed by an escrow or trust containing sufficient U.S. Government or U.S. Government agency securities,
	which ensure the timely payment of principal and interest. Such investments are normally considered to
	be equivalent to AAA rated securities.
(5)	This debt has been restructured to accommodate capital maintenance at the facility. Major highlights of the
	debt restructuring include the following: (1) the principal balance outstanding on and after December 1, 2007,
	shall accrue interest at a rate of 6.500% per annum commencing December 1, 2007; (2) the interest shall
	accrue but not be payable on June 1, 2008 or December 1, 2008, but shall instead be deferred and paid by
	the end of calendar year 2011; (3) no principal component shall be pre-payable from the Minimum Sinking
	Fund Account during calendar years 2008 and 2009 but such pre-payments shall recommence beginning in
	calendar year 2010 according to a revised schedule. Management believes that the restructuring is in the
	best interest of Fund shareholders and that it is more-likely-than-not that the borrower will fulfill its
	obligation. Consequently, the Fund continues to accrue interest on this obligation.
(6)	Variable Rate Demand Preferred Shares, at Liquidation Value as a percentage of Total Investments is 29.9%.
N/R	Not rated.
WI/DD	Purchased on a when-issued or delayed delivery basis.
(ETM)	Escrowed to maturity.
(IF)	Inverse floating rate investment.
(UB)	Underlying bond of an inverse floating rate trust reflected as a financing transaction.

Item 2. Controls and Procedures.

a.   The registrant's principal executive and principal financial officers, or persons performing similar functions, have concluded that the registrant's disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940, as amended (the "1940 Act") (17 CFR 270.30a-3(c))) are effective, as of a date within 90 days of the filing date of this report that includes the disclosure required by this paragraph, based on their evaluation of the controls and procedures required by Rule 30a-3(b) under the 1940 Act (17 CFR 270.30a-3(b)) and Rule 13a-15(b) or 15d-15(b) under the Securities Exchange Act of 1934 (17 CFR 240.13a-15(b) or 240.15d-15(b)).

b.   There were no changes in the registrant's internal control over financial reporting (as defined in Rule 30a-3(d) under the 1940 Act (17 CFR 270.30a-3(d)) that occurred during the registrant's last fiscal quarter that have materially affected, or are reasonably likely to materially affect, the registrant's internal control over financial reporting.

Item 3. Exhibits.

File as exhibits as part of this Form a separate certification for each principal executive officer and principal financial officer of the registrant as required by Rule 30a-2(a) under the 1940 Act (17 CFR 270.30a-2(a)), exactly as set forth below: See EX-99 CERT attached hereto.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

(Registrant)  Nuveen California Municipal Market Opportunity Fund, Inc. 

By (Signature and Title)     /s/ Kevin J. McCarthy                    

                                                   Kevin J. McCarthy

                                                   Vice President and Secretary

Date         July 30, 2010        

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

By (Signature and Title)     /s/ Gifford R. Zimmerman                    

                                                    Gifford R. Zimmerman

                                                  Chief Administrative Officer (principal executive officer) 

Date         July 30, 2010        

By (Signature and Title)     /s/ Stephen D. Foy                              

                                                   Stephen D. Foy

                                                  Vice President and Controller (principal financial officer) 

Date        July 30, 2010