(MKS LOGO)

EXHIBIT 99.1

Contact: Seth H. Bagshaw
Vice President, Chief Financial Officer & Treasurer
Telephone: 978.645.5578

MKS Instruments Reports Fourth Quarter and
Full Year 2014 Financial Results

Andover, Mass., January 28, 2015 — MKS Instruments, Inc. (NASDAQ: MKSI), a global provider of technologies that enable advanced processes and improve productivity, today reports fourth quarter and full year 2014 financial results.

Financial Results

Fourth Quarter Financial Results

Sales were $203 million, an increase of 9% from $187 million in the third quarter of 2014, and similar to sales in the fourth quarter of 2013 which were $204 million.

Fourth quarter net income was $34.2 million, or $0.64 per diluted share, compared to net income of $29.1 million, or $0.55 per diluted share in the third quarter of 2014, and $20.2 million, or $0.38 per diluted share in the fourth quarter of 2013.

Non-GAAP net earnings, which exclude special charges and credits, were $29.1 million, or $0.54 per diluted share, compared to $22.8 million, or $0.43 per diluted share in the third quarter of 2014, and $22.3 million, or $0.42 per diluted share in the fourth quarter of 2013.

Full Year Results

Sales were $781 million, an increase of 17% from $669 million in 2013. Net income was $115.8 million, or $2.16 per diluted share, compared to $35.8 million, or $0.67 per diluted share in 2013. Non-GAAP net earnings were $101.2 million, or $1.89 per diluted share, compared to $48.4 million, or $0.90 per diluted share in 2013. Cash and investments at December 31^st were $592 million, or approximately $11.14 per share. Total book value, net of goodwill and intangibles, was $843 million or approximately $15.86 per share.

Gerald Colella, Chief Executive Officer and President, said, “I’m very pleased with our strong financial and operational performance in 2014. Sales increased by 17%, non-GAAP net earnings more than doubled, and we made excellent progress toward our strategic goals. In addition, we deployed $143 million of capital during the year for the acquisition of Granville-Phillips, share repurchases and cash dividends. Business levels in our core market continue to be very healthy entering 2015 and we remain focused on our strategic initiatives and increasing long-term shareholder value.

“Based on current business levels, we expect that sales in the first quarter of 2015 may range from $195 to $215 million, and at these volumes, our non-GAAP net earnings could range from $0.45 to $0.60 per share and GAAP net income could range from $0.43 to $0.57 per share.”

Conference Call Details

A conference call with management will be held on Thursday, January 29, 2015 at 8:30 a.m. (Eastern Time). To participate in the conference call, please dial (877) 212-6076 for domestic callers and (707) 287-9331 for international callers, and an operator will connect you. Participants will need to provide the operator with the Conference ID of 45798423, which has been reserved for this call. A live and archived webcast of the call will be available on the company’s website at www.mksinst.com.

Use of Non-GAAP Financial Results

Non-GAAP amounts exclude amortization of acquired intangible assets, costs associated with completed acquisitions, an inventory step-up adjustment related to an acquisition, restructuring charges, an excess and obsolete charge related to a unique product in a solar application, a benefit related to an insurance reimbursement, supplemental executive retirement costs, discrete tax benefits and charges, and the related tax effect of these adjustments. These non-GAAP measures are not in accordance with Accounting Principles Generally Accepted in the United States of America (GAAP). MKS’ management believes the presentation of these non-GAAP financial measures is useful to investors for comparing prior periods and analyzing ongoing business trends and operating results.

About MKS Instruments

MKS Instruments, Inc. is a global provider of instruments, subsystems and process control solutions that measure, control, power, monitor and analyze critical parameters of advanced manufacturing processes to improve process performance and productivity. Our products are derived from our core competencies in pressure measurement and control, materials delivery, gas composition analysis, control and information technology, power and reactive gas generation, and vacuum technology. Our primary served markets are manufacturers of capital equipment for semiconductor devices, and for other thin film applications including flat panel displays, solar cells, light emitting diodes, data storage media, and other advanced coatings. We also leverage our technology in other markets with advanced manufacturing applications including medical equipment, pharmaceutical manufacturing, energy generation and environmental monitoring.

Forward-Looking Statements

This release contains projections or other forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, Section 27 of the Securities Act, and Section 21E of the Securities Exchange Act regarding MKS’ future growth and the future financial performance of MKS. These projections or statements are only predictions. Actual events or results may differ materially from those in the projections or other forward-looking statements set forth herein. Among the important factors that could cause actual events to differ materially from those in the projections or other forward-looking statements are the fluctuations in capital spending in the semiconductor industry, and other advanced manufacturing markets, fluctuations in net sales to MKS’ major customers, potential fluctuations in quarterly results, the challenges, risks and costs involved with integrating the operations of MKS and any acquired companies, dependence on new product development, rapid technological and market change, acquisition strategy, manufacturing and sourcing risks, volatility of stock price, international operations, financial risk management, and future growth subject to risks. Readers are referred to MKS’ filings with the Securities and Exchange Commission, including its most recent Annual Report on Form 10-K and Quarterly Reports on Form 10-Q for a discussion of these and other important risk factors concerning MKS and its operations. MKS is under no obligation to, and expressly disclaims any obligation to, update or alter its forward-looking statements, whether as a result of new information, future events or otherwise.

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MKS Instruments, Inc.
Unaudited Consolidated Statements of Operations
(In thousands, except per share data)

Note 1: In the fourth quarter of 2014, we recorded $1.4 million of withholding tax related to a foreign intercompany dividend.

Note 2: Reserve releases related to the settlement of audits and expiration of the statute of limitations.

Note 3: In the fourth quarter of 2014, we recorded a tax benefit of $3.2 million related to a German NOL resulting from a change in tax status and we recorded a $1.4 million tax credit for the reinstatement of the U.S. research credit for the full year 2014. In the third quarter of 2014, we recorded a tax benefit of $3.3 million related to a foreign intercompany dividend to the U.S.

Note 4: Inventory step-up adjustment related to the Granville-Phillips acquisition which closed during the second quarter of 2014.

Note 5: In the third and fourth quarters of 2014, we recorded restructuring charges primarily for severance costs related to a reduction in workforce, primarily at one of our foreign subsidiaries.

Note 6: In the fourth quarter of 2013, the Company’s Chief Executive Officer retired and $2.6 million of costs related to his supplemental executive retirement plan and other benefits were recognized and recorded in selling, general and administrative expenses.

Note 7: The Non-GAAP net earnings and Non-GAAP net earnings per share amounts exclude amortization of intangible assets, restructuring costs, an inventory step-up adjustment related to an acquisition, certain supplemental executive retirement costs, discrete tax benefits and charges, and the related tax effect of these adjustments to reflect the expected full year effective tax rate in the related quarter.

Note 8: The Non-GAAP income from operations and Non-GAAP operating margin percentages exclude amortization of intangible assets, restructuring costs, an inventory step-up adjustment related to an acquisition and certain supplemental executive retirement costs.

Note 9: The Non-GAAP gross profit amounts and Non-GAAP gross profit percentages exclude an inventory step-up adjustment related to an acquisition.

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MKS Instruments, Inc.
Unaudited Consolidated Statements of Operations
(In thousands, except per share data)

Note 1: In 2014, we recorded $1.4 million of withholding tax related to a foreign intercompany dividend. In 2013, we incurred income tax charges of $6.5 million related to an election to pay currently, at a substantially reduced rate, taxes on certain accumulated earnings from the years 2001 to 2011 of one of our foreign subsidiaries.

Note 2: In 2014, we recorded a tax benefit of $3.3 million related to a foreign intercompany dividend to the U.S and a tax benefit of $3.2 million related to a German NOL resulting from a change in tax status. We also recorded a $1.4 million credit for the reinstatement of the U.S. research credit for the full year 2014. In 2013, we recorded $1.2 million in credits against U.S. tax expense on amended returns related to prior years and a tax benefit of $2.4 million related to the American Taxpayer Relief Act of 2012 on January 2, 2013.

Note 3: In 2014, we recorded $14.6 million in credits for reserve releases related to the settlement of audits and expiration of the statute of limitations.

Note 4: In 2013, we incurred $6.4 million of special charges, which is included in cost of sales, for obsolete inventory related to a unique product in a solar application in which slowing market conditions provide uncertainty as to the net realizable value of this inventory.

Note 5: In 2012, we incurred $5.3 million in charges to settle litigation with former shareholders of one of our former subsidiaries. This litigation was long standing and the decision to reach a settlement was made to eliminate future legal expenses related to the suit. In 2013, we recovered $1.1 million from our insurance company relating to the prior year legal settlement.

Note 6: In 2014, we incurred legal and filing fees related to the Granville-Phillips acquisition, which closed during the second quarter of 2014. In 2013 we incurred legal fees related to the acquisition of Alter S.r.l., in March 2013.

Note 7: Inventory step-up adjustment related to the Granville-Phillips acquisition which closed during the second quarter of 2014.

Note 8: In 2014 and 2013, we recorded restructuring charges primarily related to reductions in workforce and the consolidation of certain facilities.

Note 9: In 2013, the Company’s Chief Executive Officer retired and $2.6 million of costs related to his supplemental executive retirement plan and other benefits were recognized and recorded in selling, general and administrative expenses.

Note 10: The Non-GAAP net earnings and Non-GAAP net earnings per share amounts exclude amortization of intangible assets, restructuring costs, costs associated with acquisitions, an inventory step-up adjustment related to an acquisition, a benefit related to an insurance reimbursement, an excess and obsolete charge related to a unique product in a solar application, certain supplemental executive retirement costs, discrete tax benefits and charges, and the related tax effect of these adjustments.

Note 11: The Non-GAAP income from operations and Non-GAAP operating margin percentages exclude amortization of intangible assets, restructuring costs, costs associated with acquisitions, an inventory step-up adjustment related to an acquisition, an excess and obsolete charge related to a unique product in a solar application, a benefit related to an insurance reimbursement and certain supplemental executive retirement costs.

Note 12: The Non-GAAP gross profit amounts and Non-GAAP gross profit percentages exclude an excess and obsolete charge related to a unique product in a solar application and an inventory step-up adjustment related to an acquisition.

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MKS Instruments, Inc.
Reconciliation of GAAP Income Tax Rate to Non-GAAP Income Tax Rate
(In thousands)

Note 1: In the fourth quarter of 2014, we recorded $1.4 million of withholding tax related to a foreign intercompany dividend. In 2013, we incurred income tax charges of $6.5 million related to an election to pay currently, at a substantially reduced rate, taxes on certain accumulated earnings from the years 2001 to 2011 of one of our foreign subsidiaries.

Note 2: In the fourth quarter of 2014, we recorded a tax benefit of $3.2 million related to a German NOL resulting from a change in tax status and we recorded a $1.4 million tax credit for the reinstatement of the U.S. research credit for the full year 2014. In the third quarter of 2014, we recorded a tax benefit of $3.3 million related to a foreign intercompany dividend to the U.S. In 2013, we recorded $1.2 million in credits against U.S. tax expense on amended returns related to prior years and a tax benefit of $2.4 million related to the American Taxpayer Relief Act of 2012 on January 2, 2013.

Note 3: We recorded credits for reserve releases related to the settlement of audits and expiration of the statute of limitations.

Note 4: In 2013, we incurred $6.4 million of special charges, which is included in cost of sales, for obsolete inventory related to a unique product in a solar application in which slowing market conditions provide uncertainty as to the net realizable value of this inventory.

Note 5: In 2014 and 2013, we recorded restructuring charges primarily related to reductions in workforce and the consolidation of certain facilities.

Note 6: In 2014 we incurred legal and filing fees related to the Granville-Phillips acquisition, which closed during the second quarter of 2014. In 2013 we incurred legal fees related to the acquisition of Alter S.r.l., in March 2013.

Note 7: Inventory step-up adjustment related to the Granville-Phillips acquisition which closed during the second quarter of 2014.

Note 8: In 2012, we incurred $5.3 million in charges to settle litigation with former shareholders of one of our former subsidiaries. This litigation was long standing and the decision to reach a settlement was made to eliminate future legal expenses related to the suit. In 2013, we recovered $1.1 million from our insurance company relating to the prior year legal settlement.

Note 9: In the 2013, the Company’s Chief Executive Officer retired and $2.6 million of costs related to his supplemental executive retirement plan and other benefits were recognized and recorded in selling, general and administrative expenses.

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MKS Instruments, Inc.
Reconciliation of Q1-15 Guidance — GAAP Net Income to Non-GAAP Net Earnings
(In thousands, except per share data)

Note 1: The Non-GAAP adjustments are tax effected at the estimated Q1-15 tax rate of 29%.

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MKS Instruments, Inc.
Unaudited Consolidated Balance Sheet
(In thousands)

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