(MKS LOGO)

EXHIBIT 99.1

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

MKS Instruments Reports Q3 2014 Financial Results

Andover, Mass., October 22, 2014 — MKS Instruments, Inc. (NASDAQ: MKSI), a global provider of technologies that enable advanced processes and improve productivity; today reports third quarter 2014 financial results.

Third Quarter Financial Results

Sales were $187 million, an increase of 1% from $185 million in the second quarter of 2014, and an increase of 12% from $166 million in the third quarter of 2013.

Third quarter net income was $29.1 million, or $0.55 per diluted share, compared to net income of $21.2 million, or $0.40 per diluted share in the second quarter of 2014, and $2.5 million, or $0.05 per diluted share in the third quarter of 2013. Net income in the quarter includes discrete tax credits of $9.5 million.

Non-GAAP net earnings, which exclude special charges and credits, were $22.8 million, or $0.43 per diluted share, compared to $22.6 million, or $0.42 per diluted share in the second quarter of 2014, and $13.3 million, or $0.25 per diluted share in the third quarter of 2013.

In the third quarter, the board of directors authorized a quarterly cash dividend of $0.165 per share, and paid a dividend of $8.8 million on September 12^th.

Gerald Colella, Chief Executive Officer and President, said, “The third quarter was another strong quarter financially for MKS. Sales came in at the high end of our guidance, with profitability exceeding our expectations. Semiconductor sales were relatively stable compared to the second quarter and remained stronger than expected, while sales to all other markets further increased sequentially — a reflection of the contribution from Granville-Phillips as well as our continued emphasis on these adjacent markets.

“Technology changes continue to positively impact our business. As we look to the fourth quarter, we see continued strength in both our semiconductor and other advanced markets. As we operate within this healthy business environment, we continue to make refinements to our operating structure and improvements to our profitability — redeploying resources to strategic and high-growth areas and continuously finding ways to streamline our cost structure.

“Based on these factors, and looking at current business levels, we anticipate that sales in the fourth quarter may range from $185 million to $200 million, and at these volumes, our non-GAAP net earnings could range from $0.42 to $0.53 per share.”

Conference Call Details

A conference call with management will be held on Thursday, October 23, 2014 at 8:30 a.m. (EDT). 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 93299773, 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, 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 third quarter of 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: For the three months ended September 30, 2013, we recorded $1.2 million in credits against U.S. tax expense on amended returns related to prior years.

Note 3: For the three months ended September 30, 2014, we recorded $6.1 million in credits for reserve releases related to the settlement of audits and expiration of the statute of limitations.

Note 4: For the three months ended September 30, 2014, we recorded a tax benefit of $3.3 million related to a foreign dividend to the U.S.

Note 5: For the three months ended September 30, 2013, cost of sales includes $6.4 million of special charges for obsolete inventory related to a unique product in a solar application in which slowing market conditions provided uncertainty as to the net realizable value of this inventory.

Note 6: The three months ended June 30, 2014, included acquisition costs comprised mainly of legal fees related to the Granville-Phillips acquisition which closed during the second quarter of 2014.

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

Note 8: The three months ended September 30, 2014 includes restructuring charges primarily for severance costs related to a reduction in work force at one of our foreign subsidiaries. The three months ended September 30, 2013 includes restructuring charges primarily for severance related costs related to the consolidation of certain facilities.

Note 9: The Non-GAAP net earnings and Non-GAAP net earnings per share amounts exclude amortization of intangible assets, restructuring costs, costs associated with completed acquisitions, an inventory step-up adjustment related to an acquisition, an excess and obsolete charge related to a unique product in a solar application, 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 10: The Non-GAAP income from operations and Non-GAAP operating margin percentages exclude amortization of intangible assets, restructuring costs, costs associated with completed acquisitions, an inventory step-up adjustment related to an acquisition and an excess and obsolete charge related to a unique product in a solar application.

Note 11: The Non-GAAP gross profit amounts and Non-GAAP gross profit percentages exclude an excess and obsolete inventory 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.
Unaudited Consolidated Statements of Operations
(In thousands, except per share data)

Note 1: For the nine months ended September 30, 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: For the nine months ended September 30, 2013, we recorded $1.2 million in credits against U.S. tax expense on amended returns related to prior years.

Note 3: For the nine months ended September 30, 2014, we recorded $11.2 million in credits for reserve releases related to the settlement of audits and expiration of the statute of limitations.

Note 4: For the nine months ended September 30, 2014, we recorded a tax benefit of $3.3 million related to a foreign dividend to the U.S. For the nine months ended September 30, 2013, we recorded a tax benefit of $2.4 million related to the American Taxpayer Relief Act of 2012 on January 2, 2013.

Note 5: For the nine months ended September 30, 2013, cost of sales includes $6.4 million of special charges 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 6: In the third quarter of 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 the second quarter of 2013, we recovered $1.1 million from our insurance company relating to the prior year legal settlement.

Note 7: The nine months ended September 30, 2014 includes acquisition costs comprised of legal fees and filing fees related to the Granville-Phillips acquisition which closed during the second quarter of 2014. The nine months ended September 30, 2013 includes acquisition costs comprised of legal fees related to the Company’s acquisition of Alter S.r.l., in March 2013.

Note 8: Inventory step-up adjustment related to the Granville-Phillips acquisition which closed during the second quarter of 2014.

Note 9: The nine months ended September 30, 2014 includes restructuring charges primarily for severance related costs related to a reduction in work force at one of our foreign subsidiaries. The nine months ended September 30, 2013 includes restructuring charges primarily for severance related costs related to the consolidation of certain facilities.

Note 10: The Non-GAAP net earnings and Non-GAAP net earnings per share amounts exclude amortization of intangible assets, restructurings, 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, 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 period.

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

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 third quarter of 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: For the three and nine months ended September 30, 2013, we recorded $1.2 million in credits against U.S. tax expense on amended returns related to prior years.

Note 3: For the three and nine months ended September 30, 2014, we recorded $6.1 million and $11.2 million in credits, respectively, for reserve releases related to the settlement of audits and expiration of the statute of limitations.

Note 4: For the three and nine months ended September 30, 2014, we recorded a tax benefit of $3.3 million related to a foreign dividend to the U.S. For the nine months ended September 30, 2013, we recorded a tax benefit of $2.4 million related to the American Taxpayer Relief Act of 2012 on January 2, 2013.

Note 5: Cost of sales for the three months ended September 30, 2013, includes $6.4 million of special charges for obsolete inventory related to a unique product in a solar application in which slowing market conditions provided uncertainty as to the net realizable value of this inventory.

Note 6: The three and nine months ended September 30, 2014 includes restructuring charges primarily for severance related costs related to a reduction in work force at one of our foreign subsidiaries. The three and nine months ended September 30, 2013 includes restructuring charges primarily for severance related costs related to the consolidation of certain facilities.

Note 7: The nine months ended September 30, 2014 includes acquisition costs comprised of legal fees and filing fees related to the Granville-Phillips acquisition which closed during the second quarter of 2014. The nine months ended September 30, 2013 includes acquisition costs comprised of legal fees related to the Company’s acquisition of Alter S.r.l., in March 2013.

Note 8: Inventory step-up adjustment related to the Granville-Phillips acquisition which closed during the second quarter of 2014.

Note 9: In the third quarter of 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 the second quarter of 2013, we recovered $1.1 million from our insurance company relating to the prior year legal settlement.

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MKS Instruments, Inc.
Reconciliation of Q4-14 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 Q4-14 tax rate of 31%.

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

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