Exhibit 99.1

RUBICON TECHNOLOGY, INC. REPORTS FIRST QUARTER

2016 RESULTS OF OPERATIONS

Bensenville, Ill. – May 10, 2016— Rubicon Technology, Inc. (NASDAQ:RBCN), a leading provider of sapphire substrates and products to the LED, optical and semiconductor industries, today reported financial results for its first quarter ended March 31, 2016.

The Company reported first quarter revenue of $4.3 million, up $1.8 million from the prior quarter revenue of $2.5 million due primarily to increased wafer sales, particularly PSS wafer sales which accounted for most of the increase. Another significant rise is PSS wafer sales is expected in the third quarter based on current customer projections.

Bill Weissman, Rubicon’s CEO, said, “We expect meaningful increases in six-inch PSS sales over the course of this year because of our large diameter capability and vertical integration. We are working diligently to reduce wafer cost in order to fully benefit from this opportunity.”

The Company’s first quarter GAAP loss per share was $0.28 as compared with a GAAP loss of $0.49 in the prior quarter, which included certain non-cash charges. The fourth quarter non-GAAP loss per share excluding those charges was $0.38.

The Company also continues to work on developing its optical sapphire business and reiterated its expectations of moving two new technologies into production this year, as LANCE large window growth and SapphirEX coating technologies (patents pending) both reported additional important milestones being met in the quarter.

Excess sapphire capacity in the market continues to depress sapphire pricing. As a consequence, the Company has been limiting the amount of two and four-inch core sold in recent quarters due to the particularly challenging pricing. The Company continues to work with developers of some very interesting potential new applications for sapphire which could open up new markets.

Mr. Weissman added, “We continue to work with the developers of some very interesting potential new applications for sapphire which fit particularly well with Rubicon’s unique set of sapphire knowledge and capabilities. Over the next several months, we expect to see meaningful developments in some of these new market opportunities, as well as developments in our new technologies and further progress in product cost reductions. As these projects unfold, our management team and Board of Directors will continue to make strategic decisions that we believe will maximize Rubicon’s value.”

Second Quarter 2016 Guidance

The Company expects second quarter revenue and GAAP loss per share to be similar to the first quarter. Revenue growth is expected to resume in the third quarter primarily from increasing PSS wafer sales.

Conference Call Details

Rubicon will host a conference call at 5:00 p.m. Eastern time on May 10, 2016 to review the first quarter 2016 results and the second quarter outlook. The conference call will be available to the public through a live audio web broadcast via the Internet. Log on through the Investor Relations section of Rubicon’s website at http://ir.rubicontechnology.com. An audio replay of the call will be available approximately two hours after the conclusion of the call. The audio replay will remain available until 11:59 p.m. Eastern time on May 17, 2016, and can be accessed by dialing (877) 344-7529 or (412) 317-0088 (international). Callers should reference conference ID 10085975. The webcast will be archived on the Company’s website.

About Rubicon Technology, Inc.

Rubicon Technology, Inc. is a vertically integrated advanced materials provider specializing in monocrystalline sapphire for applications in light-emitting diodes (LEDs), optical systems and specialty electronic devices. Rubicon has a proprietary technology platform and expertise extending from the preparation of raw aluminum oxide through sapphire crystal growth and fabrication to large-diameter polished sapphire windows and wafers and patterned sapphire substrates (PSS), enabling Rubicon to supply custom sapphire products with superior quality and precision. Rubicon is ISO 9001 certified and ITAR registered.

Further information is available at http://www.rubicontechnology.com.

Forward-Looking Statements

Certain of the statements in this release, particularly those preceded by, followed by or including the words “believes,” “expects,” “anticipates,” “intends,” “should,” “estimates,” or similar expressions, or those relating to or anticipating financial results for periods beyond the end of the first quarter of 2016, constitute “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. For those statements, the Company claims the protection of the safe harbor for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995. These forward-looking statements are based on our current expectations, estimates and projections about our industry, management’s beliefs and certain assumptions made by us. These statements are subject to risks and uncertainties that could cause actual results to differ materially from those expressed in, or implied by, the statements. These risks and uncertainties include changes in the average selling prices of sapphire products, our successful development and market acceptance of new products, dependence on key customers, potential disruptions in our supply of electricity, changes in our product mix, our ability to protect our intellectual property rights, the competitive environment, the availability and cost of raw materials, the cost of compliance with environmental standards, the ability to make effective acquisitions and successfully integrate newly acquired businesses into existing operations and other risks and uncertainties described in

the Company’s 2015 Form 10-K as amended and other filings with the Securities and Exchange Commission. For these reasons, readers are cautioned not to place undue reliance on the Company’s forward-looking statements. Any forward-looking statement that the Company makes speaks only as of the date of such statement, and the Company undertakes no obligation to update any forward-looking statements, whether as a result of new information, future events or otherwise. Comparisons of results for current and any prior periods are not intended to express any future trends or indications of future performance, unless expressed as such, and should only be viewed as historical data.

CONTACT:

Dee Johnson

Vice President, Investor Relations

847-457-3426

Rubicon Technology, Inc.

Condensed Consolidated Balance Sheets

(in thousands)

Rubicon Technology, Inc.

Condensed Consolidated Statements of Operations (unaudited)

(in thousands except share and per share amounts)

Rubicon Technology, Inc.

Condensed Consolidated Statements of Cash Flows (unaudited)

(in thousands)

Rubicon Technology, Inc.

Revenue by Product Group

(in thousands)

Non-GAAP Disclosures

In addition to the GAAP results provided in this release, the Company has provided non-GAAP operating loss and non-GAAP loss per share for the fourth quarter of 2015. The Company’s management believes that providing these non-GAAP financial measures better enables investors to understand and evaluate the Company’s historical and prospective operating performance. The non-GAAP measures exclude the impact of certain non-cash charges which are described in the footnotes to the table below. Management excludes these items because they believe the impacts do not reflect expected future results and that their exclusion aids in the comparison of the Company’s current results with past and future operating results. These non-GAAP financial measures may have limitations as analytical tools, and these measures should not be considered in isolation or as a substitute for analysis of the Company’s results as reported under GAAP. Other Companies may calculate these non-GAAP financial measures differently than the Company does limiting the usefulness of those measures for comparative purposes.

Rubicon Technology, Inc.

Q4’15 Reconciling Items to Condensed Consolidated Statement of Operations GAAP to Non-GAAP (unaudited)

(in thousands except share and per share amounts)