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FORM 6-K

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C.  20549

REPORT OF FOREIGN PRIVATE ISSUER
PURSUANT TO RULE 13a-16 OR 15d-16 OF
THE SECURITIES EXCHANGE ACT OF 1934

For the month of August 2010

Commission File Number 1-15224

Energy Company of Minas Gerais

(Translation of Registrant’s Name Into English)

Avenida Barbacena, 1200

30190-131 Belo Horizonte, Minas Gerais, Brazil

(Address of Principal Executive Offices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F x  Form 40-F o

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1): o

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): o

Indicate by check mark whether by furnishing the information contained in this Form, the registrant is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes o  No x

If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b):  N/A

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Index

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Forward-Looking Statements

This report contains statements about expected future events and financial results that are forward-looking and subject to risks and uncertainties.  Actual results could differ materially from those predicted in such forward-looking statements.  Factors which may cause actual results to differ materially from those discussed herein include those risk factors set forth in our most recent Annual Report on Form 20-F filed with the Securities and Exchange Commission.  CEMIG undertakes no obligation to revise these forward-looking statements to reflect events or circumstances after the date hereof, and claims the protection of the safe harbor for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995.

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SIGNATURES

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

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1.             Second Quarter 2010 Earnings Release, Companhia Energética de Minas Gerais — CEMIG

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EARNINGS RELEASE

2Q 2010

This text is a translation, provided for information only. The original text in Portuguese is the legally valid version.

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(Figures in R$ ’000, except where otherwise stated)

·              2Q10 HEADLINES

·                  Ebitda of R$ 874 million, and Adjusted Ebitda of R$ 1.1 Billion

·                  Net income of R$ 291 million, and Adjusted Net Income of R$ 477 million

·                  Net sales revenue of R$ 3 billion

·                  Cash position of R$ 4 billion

·                  Electricity sold in 2Q10: 16,769 GWh, 12.50% increase over the 2Q09

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·                 Appreciation in value of Cemig’s shares and ADRs — 3 months to June 30:

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·              Economic summary

(R$ million)

·              Consolidated electricity market

In 2Q10 Cemig sold a total of 16,768 GWh, 12.5% more than in the same period of 2009.

As well as the growth in consumption by all the categories of final consumers, one highlight of the quarter was the high volume of electricity traded on the CCEE, which was 311% higher, at 1,853 GWh in 2Q10, than in 2Q09 (450 GWh).

This expansion arises from the higher volume of secondary energy sold than in 2Q09: sales to other concession holders were 9.52% lower, due to the ending of contracts signed by Cemig in the Adjustment Auction in 2009.

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Consolidated sales volume- MWh

(*) The information in MWh has not been reviewed by the external auditors.

Sales to final consumers

The total volume of electricity sold to final consumers in the second quarter of 2010 was 11,718 GWh, or 7.22% more than the 10,929 GWh sold in the second quarter of 2009.

This basically reflects the resumption of economic activity, especially reflected in the industrial and residential user categories, in which consumption was up 9.06% and 3.99% respectively.

This chart shows electricity sales by category of final consumer:

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Sales volume, by consumer type (%), 2Q10

Sales to industrial consumers were around 52% of the total sold, followed by the residential category with 21%, and the commercial category with 14%.

In the six-month period ending in June 2010 sales to final consumers totaled 22,469 GWh, 2.60% more than in 2Q09 (21,901 GWh).

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·      The market of Cemig GT

Cemig GT sold 9,088 GWh in 2Q10, 5.67% more than in 2Q09 (8600 GWh).

The lower total of wholesale supply to other concession holders is basically due to the ending of the contracts signed by Cemig GT in the 2009 Adjustment Auction, when the electricity was again placed in the free market, which expanded significantly, led by the industrial consumer category, which was 12.60% higher, at 4,510 GWh, compared to 4,006 GWh in 2Q09.

As a result of the higher volume of secondary electricity sold in the period, electricity trading transactions on the CCE were 339% higher, at 1120 GWh, compared to 255 GWh in 2Q09.

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·      The market of Cemig D

Cemig D sold 5,710 GWh in 2Q10, 3.47% more than in 2Q09.

This increase reflects the recovery in economic activity in the distributor’s concession area, led by the residential, commercial and rural consumer categories. As a result of migration of consumers from the captive market to the free market, sales to the industrial category were 1.43% lower in 2Q10 than in 2Q09.

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Adjusted for this migration, consumption by the industrial category was 14% higher, representing a volume of sales to final consumers 7% higher.

·            The market of Light

For more details on Light’s sales in the second quarter of 2010, please see this link:

http://www.mzweb.com.br/light/web/arquivos/Light_Press_Release_2T10_en.pdf

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·              Consolidated operational revenue

Revenue from supply of electricity

Revenue from supply of electricity in 2Q10 was R$ 3,718,053, 1.29% more than in 2Q09 (R$ 3,670,692).

The main factors affecting revenue in 2010 were:

·             Tariff Adjustment with average impact on consumer tariffs of +1.67%, starting from April 8th, 2010.

·             Volume of energy invoiced to final consumers (excluding Cemig’s own internal consumption) 7.22% higher than in 2Q09.

The volume of electricity sold to other concession holders in 2Q10 was 9.52% lower than in 2Q09, and average price in these sales was also lower, at R$ 105.14/MWh, compared to R$ 129.54/MWh in 2Q09. This reduction mainly reflected the contracts made through the Adjustment Auction that took place in 2009, which power was sold for an average price of R$ 145.00/MWh. As a result, Revenue from wholesale supply

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to other concession holders was 26.56% lower year-on-year, at R$ 335,388 in 2Q10, than in 2Q09 (R$ 456,680).

Supply to other concession holders

The volume of electricity sold to other concession holders in 2Q10 was 9.52% lower than in 2Q09, and average price in these sales was also lower, at R$ 105.14/MWh, compared to R$ 129.54/MWh in 2Q09. This reduction mainly reflected the contracts made through the Adjustment Auction that took place in 2009, which power was sold for an average price of R$ 145.00/MWh. As a result, Revenue from wholesale supply to other concession holders was 26.56% lower year-on-year, at R$ 335,388 in 2Q10, than in 2Q09 (R$ 456,680).

Revenue from use of the network — Free Consumers

This refers to the TUSD — Tariff for use of the Distribution System — arising from the charges made to Free Consumers, on energy sold, and also from the revenue for use of Cemig GT’s basic transmission grid. It was 3.44% higher in 2Q10, at that R$ 645,671, than in 2Q09 (R$ 624,195).

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As well as reflecting higher transport of electricity to free consumers, on resumption of activity by industrial clients, and migration of captive clients to the free market, the figures include revenue from the operations of the transmission company Taesa, acquired in the fourth quarter of 2009.

At the same time, the Company recorded a reduction of revenue, of R$ 64,586, from the tariff repositioning, by a negative percentage of 15.88%, applied to its revenue backdated to July 2009, in the 2010 Transmission Tariff Review. In 2009, by contrast, a Revenue item of R$ 158,090 was recorded, as a result of the Transmission Tariff Review with backdated effect covering the period from July 1st , 2005 to June 30th , 2009.

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·              EBITDA

Cemig’s Ebitda in the second quarter of 2010 was 15.60% lower than its Ebitda for the second quarter of 2009. Adjusted for the non-recurring items, it was 8.02% higher.

The 15.60% lower figure for Ebitda in 2Q10 than in 2Q09 mainly reflects the following non-recurring adjustments in the years of 2009 and 2010:

·                            In 2010 the company recorded a reduction of revenue of R$ 64,586, arising from the tariff repositioning, by a negative percentage, of 15.88%, applied to its revenue backdated to July 2009, in the 2010 Review of the Transmission Tariff.

·                            In 2009, on the other hand, the company recorded a positive revenue item of R$ 158,090, arising from the tariff repositioning under its First Transmission Tariff Review, which was an increase of 5.35%, for the period backdated to 2005.

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·                            Recognition by Cemig’s distribution company (Cemig Distribuição S.A. – Cemig D) of an expense of R$ 177,592, for settlement of a legal action brought by Rima Industrial S.A., for reimbursement of the tariff increase introduced by the DNAEE (National Water and Energy Authority) during the Cruzado economic plan of 1986.

·                            Recognition of an ICMS tax expense relating to the subsidy for the discount on tariffs for low-income consumers, in the amount of R$ 25,702, resulting from the decision to subscribe to the Tax Amnesty program put in place by the government of the State of Minas Gerais.

·                            Provisions, in 2010 and 2009, of R$ 14,246, and R$ 192,918, respectively, for the Company’s Voluntary Retirement Program.

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This table shows these non-recurring adjustments:

(Method of calculation not reviewed by our external auditors.)

·                                         Net income

In the second quarter of 2010, CEMIG reported a net income of R$ 290,516, 44.54% less than the net income of R$ 523,794 reported for the second quarter of 2009. Basically this reflects non-recurring adjustments in 2010:

·                            for the court settlement, of R$ 177,592, made by Cemig Distribuição with an industrial consumer in a legal action arising from a tariff increase made in the Cruzado economic plan (of 1986); and

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·                            recognition of a reduction of revenue, of R$ 64,586, arising from the 2010 periodic Transmission Tariff Review, which applied a tariff repositioning of — 15.88% backdated to July 2009.

When not considering these non-recurring adjustments, the net income of the 2Q10 is 13% lower than in 2Q09, with R$ 477 million and R$ 547 million, respectively.

·                                         Deductions from operational revenues

Deductions from operational revenues in 2Q10 totaled R$ 1,571,377, which was 7.86% more than in 2Q09 (R$ 1,456,890). Main year-on-year variations in the deductions from revenue were:

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The Fuel Consumption Account — CCC

The deduction from revenue for the CCC was R$ 169,797 in 2Q10, 11.67% more than in 2Q09 (R$ 152,049). This is a contribution for the costs of operation of the thermal plants in the national grid and in the isolated systems. It is shared between electricity concession holders, on a basis set by an ANEEL Resolution. This is a non-controllable cost. The amount posted for electricity distribution services is passed through in full to the tariff. For the amount posted in relation to electricity transmission services the company merely passes through the charge — it is charged to Free Consumers on the invoice for the use of the basic grid, and passed on to Eletrobrás.

CDE — Energy Development Account

The deduction from revenue for the CDE was R$ 117,392 in 2Q10, compared to R$ 101,959 in 2Q09, an increase of 15.14%. This is a non-controllable cost. The amount posted for electricity distribution services is passed through in full to the tariff. For the amount posted in relation to

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electricity transmission services the company merely passes through the charge — this part is charged to Free Consumers on the invoice for the use of the grid, and passed onto Eletrobrás.

Global Reversion Reserve — RGR

The charge for the RGR in 1Q10 was R$ 44,907, compared to R$ 43,730 in 2Q09. This is a non-controllable cost: the expense recognized in the income statement is the amount passed through to the tariff.

The other deductions from revenue are for taxes that are calculated as a percentage of invoiced revenue — hence their variations are substantially the same in percentage terms as the changes in revenue.

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·                                         Non-controllable costs

Differences between the sums of non-controllable costs, used as a reference in calculating the tariff adjustment, and disbursements actually made (also known as “CVA”), are offset in subsequent tariff adjustments. They are recorded in Assets and Liabilities. Due to a change in ANEEL’s plan of accounts, some items were transferred to Deductions from operational revenue. For more information, please see Explanatory Notes 2 and 9 to the Quarterly Information.

·                                         Operational costs and expenses (excluding Financial revenue/expenses)

Operational costs and expenses (excluding Financial revenue (expenses)) in 2Q10 totaled R$ 2,288,387, 8.48% more than in 2Q09 (R$ 2,109,426). This was mainly due to a provision, of R$ 177,592, recorded in Other expenses, arising from settlement of a legal action with a large industrial consumer in 2Q10.

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The main variations in operational expenses were:

Personnel expenses

Personnel expenses totaled R$ 298,687 in 2Q10, 33.36% less than in 2Q09 (R$ 448,231). This mainly reflects the expense on the PDV Voluntary Retirement Program, of R$ 192.918 recorded in the second quarter of 2009, compared to R$ 14,246 in 2Q10, and also the fact that the number of employees was reduced from 10,144 in June 2009 to 9,341 in June 2010.

Electricity bought for resale

The expense on electricity bought for resale in 2Q09 was R$ 918,207, 9.54% more than the expense of R$ 838,265 in 2Q09. This is in it’s major share a non-controllable cost: the expense recognized in the income statement is the amount passed on to the tariff. There is more information on this in Explanatory Note 28 to the Consolidated Quarterly Information.

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Charges for use of the transmission grid

Expenses on charges for the use of the transmission grid were R$ 186,844 in 2Q10, 11.22% higher than in 2Q09 (R$ 210,456).

These expenses, set by an ANEEL Resolution, are payable by electricity distribution and generation agents for use of the facilities that are components of the national grid. This is a non-controllable cost in the Distribution activity: the deduction from revenue recognized in the Income statement corresponds to the value actually passed through to the tariff.

Post-employment obligations

Expenses on post-employment obligations totaled R$ 44,150 in 2Q10, 27.92% more than in 2Q09 (R$ 34,515). These expenses basically represent the interest applicable to Cemig’s actuarial obligations, net of the investment yield expected from the pension plans’ assets, estimated by an external actuary. The higher expense in 2Q10 basically reflects lower expectation of revenue from the plan’s assets in 2010.

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Operational provisions

Expenses on operational provisions in 2Q10 were R$ 183,985, compared to R$ 6,876 in 2Q09. The difference reflects an item of R$ 177,592, provisioned in May 2010, arising from settlement to terminate a legal action brought by an industrial consumer relating to the tariff increase ordered by the National Water and Electricity Authority (DNAEE) by its Ministerial Order 045, of 1986.

·                                         Financial revenues (expenses)

The main factors in the difference between financial revenues/expenses in 2Q10 and 2Q09 are:

Recording of an expense, in 2Q10, of R$ 338, under Net monetary adjustment on regulatory assets (CVA, the General Agreement for the Electricity Sector, and the Deferred Tariff Adjustment), rather than a revenue, of R$ 22,325, in 2Q09. The change is mainly because the value of the regulatory assets had been reduced in 2010 — as they were partially paid off by receipt of amounts in the tariff through clients’ electricity

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bills. For further information regarding this subject see our Explanatory Notes 9 and 29 to the Consolidated Quarterly Information.

·                  Costs of loans and financings of R$ 263,018 in 2Q10, compared to R$ 150,212 in 2Q09. This reflects entry of new financings, principally the R$ 2,700,000 in debentures raised by Cemig GT (Cemig Geração e Transmissão) in March 2010.

·                  A higher figure for Monetary updating on loans and financings in Brazilian currency, at R$ 38,937 in 2Q10, compared to R$ 2,233 in 1Q09. This reflects the higher volume of funding raised, and the change in inflation indices and other indexors of contracts on the company’s loans, financings and debentures — principally the IGP-M inflation index, which was 1.15% over the period of 2Q09, and 1.53% over 2Q10.

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·                                         Income tax and Social Contribution tax

Cemig’s expenses on income tax and the Social Contribution tax in 2Q10 totaled R$ 154,747, on income of R$ 488,715 before tax effects, a percentage of 31.66%. In the second quarter of 2009 the Company’s expenses on income tax and the Social Contribution were R$ 245,493, on pre-tax profit of R$ 829,530, a percentage of 29.59%.

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·                                         Disclaimer

Some statements and assumptions in this document are projections based on the viewpoint and assumptions of management, and involve risks and uncertainties both known and unknown. Actual future results may differ materially from those expressed or implicit in such statements.

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CEMIG GT — I to III

Chart I

Operating Revenues (consolidated) - CEMIG GT
Values in million of Reais

Chart II

Operating Expenses (consolidated) - CEMIG GT
Values in millions of reais

Chart III

Statement of Results (Consolidated) - CEMIG GT
Values in millions of reais

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CEMIG D — I to IV

Chart I

CEMIG D Market

(1)               Refers to the quantity of electricity for calculation of the regulatory charges charged to free consumer clients (“

(2)               Total electricity distributed

(3)               Sum of the demand on which the TUSD is invoiced, according to demand contracted (“Portion B”).

Chart II

Operating Revenues (consolidated) - CEMIG D
Values in million of Reais

Chart III

Operating Expenses (consolidated) - CEMIG D
Values in millions of reais

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Chart IV

Statement of Results (Consolidated) - CEMIG D
Values in millions of reais

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CEMIG Consolidated charge I to XI

Chart I

Energy Sales (Consolidated)

Chart II

Energy Sales (Consolidated)

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Chart III

Sales per Company

Cemig Distribution