Exhibit 99.1

Entegris Reports Fourth-Quarter and Full-Year Results;

$100 Million Share Repurchase Authorization Announced

BILLERICA, Mass., February 9, 2016 – Entegris, Inc. (NasdaqGS: ENTG), a leading provider of yield-enhancing materials and solutions for advanced manufacturing processes, today reported its financial results for the Company’s fourth quarter and fiscal year ended December 31, 2015.

The Company recorded fourth-quarter sales of $266.8 million. Fourth-quarter net income of $17.6 million, or $0.12 per diluted share, included amortization of intangible assets of $11.4 million and aggregated acquisition and integration-related costs of $ 5.6 million associated with the April 30, 2014 acquisition of ATMI, Inc. Non-GAAP net income was $ 28.8 million, or $0.20 per diluted share.

Fiscal 2015 sales were $1.1 billion and compared to sales of $962.1 million in fiscal 2014. Net income for fiscal 2015 was $80.3 million which included amortization of intangible assets of $47.3 million and aggregated acquisition and integration-related costs of $12.7 million associated with the acquisition of ATMI, Inc. Net income of $0.57 per diluted share compared to net income of $0.06 per diluted share a year earlier. On a non-GAAP basis, net income per diluted share in fiscal 2015 was $0.85 compared with net income per diluted share of $0.69 for the year earlier.

Bertrand Loy, president and chief executive officer, said: “The fourth quarter was a strong finish to a transformational year for Entegris. We are pleased with our fourth-quarter sales of $266.8 million, particularly in light of softening trends in the semiconductor industry. Non-GAAP earnings per share of $0.20 reflected a lower gross margin which was offset by a favorable tax rate. Gross margin was primarily impacted by lower manufacturing volumes as we aggressively drove a reduction of our inventory levels, as well as accelerated customer qualification activity related to the i2M ramp. The 8 percent reduction of inventories helped us generate near record cash from operations in the quarter.”

Mr. Loy added: “For the year, we grew our top line on a constant currency basis in excess of our markets, in spite of a difficult industry environment. We generated $121 million of cash from operations, and grew our Non-GAAP earnings per share by 23 percent to a record high. We are particularly pleased with these results in a year in which we completed an effective integration of ATMI, accelerated our new product development activity, and repaid $100 million of our debt.”

Quarterly Financial Results Summary

(in millions, except per share data)

First-Quarter Outlook

For the fiscal first quarter ending April 2, 2016 the Company expects sales of $250 million to $265 million, net income of $11 million to $16 million, and net income per diluted share between $0.08 to $0.12 per share. On a non-GAAP basis, EPS is expected to range from $0.13 to $0.17 per diluted share, which reflects net income on a non-GAAP basis in the range of $19 million to $24 million, which is adjusted for expected amortization expense of approximately $11.2 million or $0.05 per share.

Share BuyBack Authorization Announced

Entegris announced that the Company’s Board of Directors has authorized the repurchase of up to $100 million of its common stock. The purchases will occur in open market transactions from time to time depending on market conditions or in accordance with a repurchase plan under SEC Rule 10b5-1.

This authorization does not obligate the Company to repurchase any dollar amount or number of shares of common stock. This authorization is in effect until February 2017 and may be suspended or discontinued at any time.

Segment Results

The Company reports its results in two business segments: Critical Materials Handling (CMH) and Electronic Materials (EM). Summary results by segment are contained in this press release.

CMH provides a broad range of products that filter, handle, dispense, and protect critical materials used in the semiconductor manufacturing process and in other high-technology manufacturing. CMH’s products and subsystems include high-purity materials packaging, fluid-handling and dispensing systems, liquid filters, as well as microenvironments that protect critical substrates such as wafers during shipping and manufacturing. CMH also provides specialized graphite components and specialty coatings for use in high-temperature applications.

EM provides high-performance materials and specialty gas management solutions that enable high-yield, cost-effective semiconductor manufacturing. EM’s products consist of specialized chemistries and performance materials, gas microcontamination control solutions, and sub-atmospheric pressure gas delivery systems for the efficient handling of hazardous gases to semiconductor process equipment.

Fourth-Quarter Results Conference Call Details

Entegris will hold a conference call to discuss its results for the fourth quarter and fiscal year on Tuesday, February 9, 2016, at 10:00 a.m. Eastern Time. Participants should dial 785-424-1675 or toll-free 888-632-3384, referencing confirmation code 2412795. Participants are asked to dial in 5 to 10 minutes prior to the start of the call. A replay of the call will be available starting February 9, 2016 at 1:00 p.m. (ET) until Monday, March 17, 2016. The replay can be accessed by using passcode 2412795 after dialing 1-719-457-0820 or 1-888-203-1112. A live and on-demand webcast of the call can also be accessed from the investor relations section of Entegris’ website at www.entegris.com.

ABOUT ENTEGRIS

Entegris is a leading provider of yield-enhancing materials and solutions for advanced manufacturing processes in the semiconductor and other high-technology industries. On April 30, 2014, Entegris acquired Danbury, CT-based ATMI, Inc. Entegris is ISO 9001 certified and has manufacturing, customer service and/or research facilities in the United States, China, France, Germany, Israel, Japan, Malaysia, Singapore, South Korea and Taiwan. Additional information can be found at www.entegris.com.

Non-GAAP Information

The Company’s condensed consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States (GAAP). Adjusted EBITDA and Adjusted Operating Income together with related measures thereof, and non-GAAP EPS, are considered “Non-GAAP financial measures” under the rules and regulations of the SEC. These financial measures are provided as a complement to financial measures provided in accordance with GAAP. We provide non-GAAP financial measures in order to better assess and measure operating performance. Management believes the non-GAAP measures better portray our baseline performance before certain gains, losses or other charges that may not be indicative of our business or future outlook. We believe these non-GAAP measures will aid investors’ overall understanding of our results by providing a higher degree of transparency for certain expenses and providing a level of disclosure that will help investors understand how we plan and measure our business. The reconciliations of GAAP to non-GAAP Statements of Operations, GAAP to Adjusted Operating Income and Adjusted EBITDA, and GAAP to Non-GAAP Earnings per Share are included elsewhere in this release.

In addition we have included pro forma segment net sales and segment profit for the Critical Materials Handling and Electronic Materials business segments for the twelve months ended December 31, 2014. Our pro forma presentation includes transactions (i) recorded by ATMI, Inc. prior to its merger with the Company and (ii) as if those business segments were configured during those prior periods to include the businesses included in those segments during the twelve

months ended December 31, 2014. We have provided this non-GAAP pro forma information to provide investors with comparative historical context for the performance of these business segments during the twelve months ended December 31, 2014. Footnotes to the Historical Non-GAAP Pro Forma Segment Information table provided elsewhere in this release reconcile this information to the corresponding GAAP information.

Forward-Looking Statements

Certain information contained in this press release may constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements are based on current management expectations only as of the date of this press release, and involve substantial risks and uncertainties that could cause actual results to differ materially from the results expressed in, or implied by, these forward-looking statements. Statements that include such words as “anticipate,” “believe,” “estimate,” “expect,” “forecast,” “may,” “will,” “should” or the negative thereof and similar expressions as they relate to Entegris or our management are intended to identify such forward-looking statements. These statements are not guarantees of future performance and involve risks, uncertainties and assumptions that are difficult to predict. These risks include, but are not limited to, fluctuations in the market price of Entegris’ stock, Entegris’ future operating results, Entegris’ ability to successfully integrate the ATMI business and achieve anticipated synergies, other acquisition and investment opportunities available to Entegris, general business and market conditions and other factors. Additional information concerning these and other risk factors may be found in previous financial press releases issued by Entegris and Entegris’ periodic public filings with the Securities and Exchange Commission, including discussions appearing under the headings “Risks Relating to our Business and Industry,” “Additional Risks Related to Our Business,” “Risks Relating to Our Indebtedness,” “Manufacturing Risks,” “International Risks,” and “Risks Related to Owning Our Securities” in Item 1A of our Annual Report on Form 10–K for the fiscal year ended December 31, 2014, filed with the U.S Securities and Exchange Commission on February 26, 2015, the discussion appearing in Part II, Item 1A of our Quarterly Report on Form 10–Q for the fiscal period ended September 26, 2015, filed with the U.S Securities and Exchange Commission on October 29, 2015, as well as other matters and important factors disclosed previously and from time to time in the filings of Entegris with the U.S. Securities and Exchange Commission. Except as required under the federal securities laws and the rules and regulations of the Securities and Exchange Commission, we undertake no obligation to update publicly any forward-looking statements contained herein.

Entegris, Inc. and Subsidiaries

Condensed Consolidated Statements of Operations

(In thousands, except per share data)

(Unaudited)

Entegris, Inc. and Subsidiaries

Condensed Consolidated Statements of Operations

(In thousands, except per share data)

(Unaudited)

Entegris, Inc. and Subsidiaries

Condensed Consolidated Balance Sheets

(In thousands)

(Unaudited)

Entegris, Inc. and Subsidiaries

Condensed Consolidated Statements of Cash Flows

(In thousands)

(Unaudited)

Entegris, Inc. and Subsidiaries

Segment Information

(In thousands)

(Unaudited)

Entegris, Inc. and Subsidiaries

Historical Non-GAAP Pro Forma Segment Information

(In thousands)

(Unaudited)

⁽¹⁾The above pro forma results include the addition of ATMI, Inc.’s net sales and segment profit amounts recorded prior to the consummation of the merger with the Company on April 30, 2014 to the Company’s reported GAAP net sales and segment profit amounts related to businesses that were transferred to the above business segments after the effectiveness of the merger and are provided as a complement to, and should be read in conjunction with, the Condensed Consolidated Statements of Operations to better facilitate the assessment and measurement of the Company’s operating performance.

The above GAAP to Non-GAAP Pro Forma Segment Information is reconciled to the Company’s GAAP figures for the quarters ended December 31, 2014 in the following footnotes.

Entegris, Inc. and Subsidiaries

GAAP to Non-GAAP Reconciliation of Statement of Operations

(In thousands, except per share data)

(Unaudited)

The above GAAP to Non-GAAP Reconciliation of Statement of Operations is provided as a complement to and should be read in conjunction with the Condensed Consolidated Statements of Operations. The above GAAP to Non-GAAP Reconciliation of Statement of Operations is provided to better facilitate the assessment and measurement of the Company’s operating performance.

Entegris, Inc. and Subsidiaries

Reconciliation of GAAP Net Income to Adjusted Operating Income and Adjusted EBITDA

(In thousands)

(Unaudited)

Entegris, Inc. and Subsidiaries

Reconciliation of GAAP Net Income to Non-GAAP Earnings per Share

(In thousands, except per share data)

(Unaudited)

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