Exhibit 99.1

FOR IMMEDIATE RELEASE

Koppers Inc. Announces Postponement of Proposed Private Offering

PITTSBURGH, January 22, 2015 – Koppers Inc., a wholly-owned subsidiary of Koppers Holdings Inc. (NYSE: KOP), announced today that it is postponing its previously announced private offering of $400 million aggregate principal amount of senior notes due 2020.

“While we remain interested in an offering, we can afford to be patient, as this offering was opportunistic in nature,” said Michael J. Zugay, chief financial officer. “Given current volatility in the markets, we prefer to postpone our offering at this time. We will potentially revisit an offering in the future if market conditions become more favorable.”

This news release shall not constitute an offer to sell, or the solicitation of an offer to buy, any securities, nor does it constitute an offer or solicitation in any jurisdiction in which such offer or solicitation is unlawful.

About Koppers

Koppers, with corporate headquarters in Pittsburgh, Pennsylvania, is an integrated global producer of carbon compounds, chemicals, and treated wood products and services for the aluminum, railroad, specialty chemical, utility, rubber, concrete, steel, residential lumber, and agriculture industries. Including our joint ventures, we serve our customers through a comprehensive global manufacturing and distribution network, with facilities located in North America, South America, Australasia, China and Europe. The stock of Koppers Holdings Inc. is publicly traded on the New York Stock Exchange under the symbol “KOP.” For more information, visit us on the Web: www.koppers.com. Questions concerning investor relations should be directed to Michael J. Zugay at 412 227 2231 or Michael W. Snyder at 412 227 2131.

Safe Harbor Statement

This news release may contain forward-looking statements based on management’s current expectations, estimates and projections. All statements that address expectations or projections about the future, including statements about the company’s strategy for growth, product development, market position, expected expenditures and financial results are forward-looking statements. Some of the forward-looking statements may be identified by words like “expects,” “anticipates,” “plans,” “intends,” “projects,” “indicates,” and similar expressions. These statements are not guarantees of future performance and involve a number of risks, uncertainties and assumptions. Many factors, including those discussed more fully elsewhere in this release and in documents filed with the Securities and Exchange Commission by Koppers,

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particularly its latest annual report on Form 10-K and quarterly report on Form 10-Q, as well as others, could cause results to differ materially from those stated. These factors include, but are not limited to, changes in the laws, regulations, policies and economic conditions, including inflation, interest and foreign currency exchange rates, of countries in which the Company does business; competitive pressures; the loss of one or more key customer or supplier relationships; customer insolvencies; successful integration of structural changes, including restructuring plans, acquisitions, divestitures and alliances; cost and availability of raw materials; and other economic, business, competitive, regulatory and/or operational factors affecting the business of Koppers generally.