Exhibit 99

PRESS RELEASE

OM GROUP ANNOUNCES SECOND QUARTER 2012 FINANCIAL RESULTS

Strong contributions from newer transformative platforms;

Significant cash flow generation

CLEVELAND – August 9, 2012 – OM Group, Inc. (NYSE: OMG) today announced financial results for the second quarter ended June 30, 2012. Diluted earnings per share from continuing operations were $(0.71), or $0.59 excluding non-cash charges relating to inventory step-up and lower-of-cost-or-market adjustments. Prior year second quarter diluted earnings per share from continuing operations were $0.80, or $0.87 as adjusted primarily for acquisition-related costs.

Second quarter consolidated net sales increased 32 percent compared with last year’s comparable quarter, increasing to $436.5 million primarily as a result of the August 2011 acquisition of VAC, partly offset by lower selling prices in its Advanced Materials business and lower volumes in its Specialty Chemicals business. Adjusted EBITDA was $53.8 million in the 2012 period compared to $45.6 million in the 2011 period, an increase of 18 percent due to the VAC acquisition. Second quarter 2012 adjusted results exclude non-cash charges of $53.9 million relating to the step-up of inventory values from the VAC acquisition and lower-of-cost-or-market charges resulting from declining rare-earth prices.

“The strong performance of our newer platforms, Magnetic Technologies and Battery Technologies, drove our enterprise results for the second quarter,” said Joe Scaminace, Chairman and Chief Executive Officer of OM Group, Inc. “In spite of challenging cobalt prices and global economic conditions, we delivered solid adjusted profits and strong cash flows for the quarter. Our strategy to diversify away from commodity businesses to value-added businesses is having the intended effect – to derive a greater portion of the Company’s profitability from transformative platforms with more predictable and sustainable longer-term earnings potential.”

OM Group generated $75 million of cash from operations in the second quarter of 2012 and finished the quarter with $318 million of cash and $662 million of debt. Lower working capital levels, particularly inventory, contributed to the performance.

Mr. Scaminace commented, “Our operating teams demonstrated our effective working capital management capabilities in the quarter, leading us to generate the highest level of operating cash flow in almost four years. This enabled us to grow our cash balances to over $300 million. We have the resources to support our strategic growth plans, which are focused on synergistic transactions within our transformative platforms.”

The Company commented that the results of its Magnetic Technologies business were driven by benefits from rare-earth pricing effects and strong sales for automotive applications. Battery Technologies delivered another quarter of high margins. In Specialty Chemicals, results were negatively impacted by weakness in Europe, which resulted in lower demand in the coatings and additives end markets. Advanced Materials was affected by lower metal prices and a scheduled annual maintenance shut-down at its principal operating facility, the effects of which more than offset the benefit from higher sales volumes. The second quarter of 2012 includes a consolidated foreign exchange gain of $5.9 million which resulted from the Company’s effective currency hedging strategy.

Looking ahead to the third quarter, the Company expects positive operating cash flow as net working capital levels continue to be optimized. The Company continues to expect lower operating profit due principally to

European weakness and minimal rare-earth pricing benefits. These profitability headwinds are expected to be partially offset by sequentially higher sales volumes in its Specialty Chemicals and Advanced Materials businesses, along with higher cobalt pricing and no additional facility shut-downs in Advanced Materials.

WEBCAST INFORMATION

OM Group has scheduled a conference call and live audio broadcast on the Web for 10 a.m. Eastern time today. Investors may access the live audio broadcast by logging on to http://investor.omgi.com. A copy of management’s presentation materials will be available on OMG’s website at the time of the call. The company recommends visiting the website at least 15 minutes prior to the webcast to download and install any necessary software. A webcast audio replay will be available on the “Investor Relations—Presentations” page of the company’s website three hours after the call.

ABOUT OM GROUP, INC.

OM Group, Inc. is a diversified specialty chemicals and materials company serving attractive global markets. The Company develops, produces and distributes innovative, high-quality chemicals, materials, products and technologies that contribute to customer success by addressing complex applications and demanding requirements. For more information, visit the company’s website at www.omgi.com.

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For more information, contact: Rob Pierce, Vice President, Finance, at +1-216-263-7489.

PRESENTATION OF NON-GAAP FINANCIAL INFORMATION

The Company is including certain non-GAAP financial measures, including adjusted operating profit, adjusted income from continuing operations and adjusted EBITDA, in this press release and the corresponding presentation materials. The Company believes that these non-GAAP financial measures facilitate a comparative assessment of the Company’s operating performance and enhance investors’ understanding of the performance of the Company’s operations during 2012 and the comparability of the 2012 results to the results of the corresponding prior period. The non-GAAP financial measures are defined and reconciled to applicable U.S. GAAP measures in this release. The non-GAAP financial information should not be construed as an alternative to reported results determined in accordance with U.S. GAAP.

FORWARD-LOOKING STATEMENTS

The foregoing discussion may include forward-looking statements for purposes of the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Such forward-looking statements are based upon specific assumptions and are subject to uncertainties and factors relating to the company’s operations and business environment, all of which are difficult to predict and many of which are beyond the control of the company. These uncertainties and factors could cause actual results of the company to differ materially from those expressed or implied in the forward-looking statements contained in the foregoing discussion. Such uncertainties and factors include: risks arising from uncertainty in worldwide economic conditions; extended business interruption at our facilities; fluctuations in the price and uncertainties in the supply of cobalt, rare earth materials and other raw materials; our ability to identify, complete and integrate acquisitions aligned with our strategy; current circumstances and developments regarding the Democratic Republic of Congo; restrictive covenants in our Senior Secured Credit Facility which may affect our ability to operate our business successfully; indebtedness may impair our ability to operate our business successfully; changes in effective tax rates or adverse outcomes resulting from examination of our income tax returns; the majority of our operations are outside the United States, which subjects us to risks that may adversely affect our operating results; level of returns on pension plan assets and changes in the actuarial assumptions; the majority of our cash is generated and held outside the United States; fluctuations in foreign exchange rates; unanticipated costs or liabilities for compliance with stringent environmental regulation; changes in environmental, health

and safety regulatory requirements; technological changes in our industry or in our customers’ products; our ability to adequately protect or enforce our intellectual property rights; disruption of our relationship with key customers or any material adverse change in their businesses; and the risk factors set forth in Part 1, Item 1a of our Annual Report on Form 10-K for the year ended December 31, 2011.

OM Group, Inc. and Subsidiaries

Unaudited Condensed Consolidated Balance Sheets

OM Group, Inc. and Subsidiaries

Unaudited Condensed Statements of Consolidated Operations

OM Group, Inc. and Subsidiaries

Unaudited Condensed Statements of Consolidated Cash Flows

OM Group, Inc. and Subsidiaries

Unaudited Segment Information

OM Group, Inc. and Subsidiaries

Unaudited Non-U.S. GAAP Financial Measures, Adjusted Operating Profit and Adjusted EBITDA

In order to assist readers of our financial statements in understanding the operating results that the Company’s management uses to evaluate the business, we are providing adjusted operating profit and adjusted EBITDA, both of which are non-U.S. GAAP financial measures. The Company’s management believes that these are important metrics in evaluating the performance of the Company’s business and in providing a baseline for evaluating and comparing our operating results. Adjusted operating profit and adjusted EBITDA are important in illustrating what our operating results would have been had we not incurred these inventory charges resulting from purchase accounting for the VAC acquisition and a lower of cost or market charge in 2012 and acquisition-related fees in 2011 and facilitate a comparative assessment of the Company’s operating performance and enhance investors’ understanding of the performance of the Company’s operations.

The table above presents a reconciliation of the Company’s U.S. GAAP operating profit—as reported to adjusted operating profit and adjusted EBITDA. The non-U.S. GAAP financial information set forth in the table above should not be construed as an alternative to reported results determined in accordance with U.S. GAAP.

OM Group, Inc. and Subsidiaries

Unaudited Non-U.S. GAAP Financial Measures

In order to assist readers of our financial statements in understanding the operating results that the Company’s management uses to evaluate the business, we are providing adjusted income from continuing operations attributable to OM Group, Inc. common stockholders and adjusted earnings per common share attributable to OM Group, Inc. common stockholders—assuming dilution, both of which are non-U.S. GAAP financial measures. The Company’s management believes that these are important metrics in evaluating the performance of the Company’s business and in providing a baseline for evaluating and comparing our operating results. Adjusted income from continuing operations attributable to OM Group, Inc. common stockholders and adjusted earnings per common share attributable to OM Group, Inc. common stockholders—assuming dilution are important in illustrating what our operating results would have been had we not incurred these inventory charges resulting from purchase accounting for the VAC acquisition and a lower of cost or market charge in 2012 and acquisition-related fees and discrete tax items in 2011 and facilitate a comparative assessment of the Company’s operating performance and enhance investors’ understanding of the performance of the Company’s operations.

The table above presents a reconciliation of the Company’s U.S. GAAP income from continuing operations attributable to OM Group, Inc. common stockholders—as reported to adjusted income from continuing operations attributable to OM Group, Inc. common stockholders and earnings per common share attributable to OM Group, Inc. common stockholders—assuming dilution—as reported to adjusted earnings per common share attributable to OM Group, Inc. common stockholders—assuming dilution. The non-U.S. GAAP financial information set forth in the table above should not be construed as an alternative to reported results determined in accordance with U.S. GAAP.