(MKS LOGO)

EXHIBIT 99.1

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

MKS Instruments Reports Q2 2013 Financial Results

Andover, Mass., July 24, 2013 — MKS Instruments, Inc. (NASDAQ: MKSI), a global provider of technologies that enable advanced processes and improve productivity; today reports second quarter 2013 financial results.

Second Quarter Financial Results

Sales were $157 million, an increase of 11% from $142 million in the first quarter, and a decrease of 12% from $177 million in the second quarter of 2012.

Second quarter net income was $7.3 million, or $0.14 per diluted share, compared to net income of $5.8 million, or $0.11 per diluted share in the first quarter of 2013, and $18.6 million, or $0.35 per diluted share in the second quarter of 2012.

Non-GAAP net earnings, which exclude special items, were $7.3 million, or $0.14 per diluted share, compared to $3.9 million, or $0.07 per diluted share in the first quarter of 2013, and $18.9 million, or $0.36 per diluted share in the second quarter of 2012. Non-GAAP net earnings in the second quarter exclude amortization of acquired intangible assets as well as $0.2 million in restructuring charges and an insurance reimbursement of $1.1 million related to a litigation settlement in the third quarter of 2012, and the related tax impact of these adjustments.

In the second quarter, the Company paid a quarterly cash dividend of $0.16 per share which was paid on June 14^th and the Company also repurchased 46 thousand shares for $1.2 million at an average price of $26.24 pursuant to the share repurchase program announced in July of 2011.

Leo Berlinghieri, Chief Executive Officer, said, “The tone at the recent Semicon West tradeshow was positive regarding long-term demand in the semiconductor market, and reports are projecting that we could continue to see modest growth as the year progresses. As the global economy continues to stabilize and grow, we are optimistic about the opportunities for MKS in both semiconductor and the other advanced markets we serve.

“Given current business levels, we anticipate that sales in the third quarter may range from $155 million to $170 million, and, at these volumes, our non-GAAP net earnings could range from $0.14 to $0.26 per share.”

Conference Call Details

A conference call with management will be held on Thursday, July 25, 2013 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 98319907, 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 net earnings and Non-GAAP net earnings per share amounts exclude amortization of acquired intangible assets, costs associated with acquisitions, restructuring charges, an insurance reimbursement related to a prior year litigation settlement, a benefit related to the enactment of the American Taxpayer Relief Act of 2012 and the related tax effect of any 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.

###

1

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

Note 1: Tax benefit related to the enactment of the American Taxpayer Relief Act of 2012 on January 2, 2013.

Note 2: 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 settlement.

Note 3: Costs related to the Company’s acquisition of Alter Power Systems S.r.l., in March 2013, are comprised of legal fees. Costs related to the Company’s acquisition of Plasmart, Inc. in 2012, are comprised of investment banking fees, legal fees and due diligence fees.

Note 4: The three month period ended June 30, 2013, includes restructuring charges primarily for severance related costs related to the consolidation of two sites.

Note 5: The Non-GAAP net earnings and Non-GAAP net earnings per share amounts exclude amortization of intangible assets, restructurings, costs associated with acquisitions, a benefit related to an insurance reimbursement, the related tax effect of these adjustments and pro-forma income tax adjustments to reflect the expected full year effective tax rate in the quarter.

2

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

Note 1: Tax benefit related to the enactment of the American Taxpayer Relief Act of 2012 on January 2, 2013.

Note 2: 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 settlement.

Note 3: Costs related to the Company’s acquisition of Alter Power Systems S.r.l., in March 2013, are comprised of legal fees. Costs related to the Company’s acquisition of Plasmart, Inc. in 2012, are comprised of investment banking fees, legal fees and due diligence fees.

Note 4: The three month period ended June 30, 2013, includes restructuring charges primarily for severance related costs related to the consolidation of two sites.

Note 5: The Non-GAAP net earnings and Non-GAAP net earnings per share amounts exclude amortization of intangible assets, restructurings, costs associated with acquisitions, a benefit related to an insurance reimbursement, the related tax effect of these adjustments and pro-forma income tax adjustments to reflect the expected full year effective tax rate in the quarter.

3

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

Note 1: Tax benefit related to the enactment of the American Taxpayer Relief Act of 2012 on January 2, 2013.

Note 2: 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 settlement.

Note 3: Costs related to the Company’s acquisition of Alter Power Systems S.r.l., in March 2013, are comprised of legal fees. Costs related to the Company’s acquisition of Plasmart, Inc. in 2012, are comprised of investment banking fees, legal fees and due diligence fees.

Note 4: The three month period ended June 30, 2013, includes restructuring charges primarily for severance related costs related to the consolidation of two sites.

Note 5: The Non-GAAP net earnings and Non-GAAP net earnings per share amounts exclude amortization of intangible assets, restructurings, costs associated with acquisitions, a benefit related to an insurance reimbursement, the related tax effect of these adjustments and pro-forma income tax adjustments to reflect the expected full year effective tax rate in the period.

4

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

5