Julius L. Katz, 74, an international trade specialist and former deputy trade representative who was chief U.S. negotiator for the North American Free Trade Agreement, died of cancer Jan. 27 at Sibley Memorial Hospital.

At his death, Mr. Katz was president of Hills & Co. International Consultants, which was founded by Carla A. Hills, the Bush administration's U.S. trade representative, under whom Mr. Katz had served during the Bush presidency.

Earlier he served 30 years in the State Department, where he became assistant secretary of state for economic and business affairs.

During his years at the agency, Mr. Katz was said to have been a major player in the formulation of U.S. foreign economic policy, and he led numerous negotiations on commodity, energy and transportation matters.

He was said to have had an encyclopedic knowledge in these areas, especially in matters concerning oil. During the Arab oil embargo and energy crisis of the early 1970s when a petroleum shortage resulted in long lines at gasoline stations, Mr. Katz was the State Department's point man and resident energy expert.

In 1980, he retired from the State Department, then became chairman and chief executive officer of DLJ Futures Inc., an arm of the Wall Street firm of Donaldson, Lufkin & Jenrette.

In 1989 Mr. Katz was nominated as deputy U.S. trade representative, with the rank of ambassador, and he served in that capacity until Bush left office in 1993.

During these years, Mr. Katz was an influential participant in the Uruguay Round of trade negotiations of the General Agreement on Trade and Tariffs, and he was the lead U.S. negotiator in the U.S.-U.S.S.R. Trade Agreement that Bush signed in 1990.

This pact, a primary economic objective of Soviet President Mikhail Gorbachev, opened the way for an eventual lifting of U.S. tariff barriers that had raised the prices of vodka, furs, caviar, petroleum and other Russian products in the United States. "Short term, it's hard to see a major impact on trade because the Soviets don't have much to sell us," Mr. Katz said at the time. "But in the long term, there are opportunities to develop trade."

As the chief negotiator of NAFTA, Mr. Katz was a primary contributor to the treaty that created a single unified market of United States, Mexico and Canada with the potential to transform the manner in which businesses in the three countries produce, distribute and sell products.

Often perceived as a curmudgeon, Mr. Katz was said to have had high expectations of himself and others, but he was also known for a sense of justice and fair play. Friends said that he had a twinkle in his eye and a delightful sense of humor and that he was rarely heard to complain.

Professionally, he was an unapologetic apostle of the principles of free trade, and he argued that it was the responsibility of the United States to lead the rest of the world toward a more open trading system. "If anything is going to happen, it's going to be because of U.S. leadership," he said in 1993.

With Hills as chairman of the board, Mr. Katz joined two other senior officials from the U.S. trade representative's office, Erin Endean and Robert Fisher, to form Hills & Co. in 1993, and he had served as its president since then.

A resident of Bethesda, Mr. Katz was born in New York. During World War II, he served in the Army in Europe, where he participated in the Allied landing at Normandy in June 1944 and in the Battle of the Bulge. After the war he came to Washington to attend George Washington University, where he graduated with a degree in international relations and economics.

In 1950 he joined the State Department, where he served for three decades. As a specialist in foreign economic policy, his duties included negotiating passenger airline fares and routes with the Japanese, keeping tabs on coffee production in Brazil, trying to find a way to stabilize world wheat prices, limiting the import of textiles from China and ensuring that U.S. flag tankers got a fair share of oil shipping.

In 1977, President Jimmy Carter named Mr. Katz to the board of directors of the Overseas Private Investment Corporation.

His awards included the Wilbur J. Carr Award and the Distinguished Honor Award from the State Department and the Distinguished Service Medal of the Department of Energy.

Survivors include his wife of 51 years, Charlotte Katz of Bethesda; three children, Barbara Spieth of Wheeling, W.Va., Linda Harrison of Houston and Lawrence Katz of Boston; a sister; and two grandchildren.