Sidney S. Mickelson, 74, a highly respected figure in the Washington art world for many years and the owner of a gallery that bore his name, died of cancer July 15 at his home in Washington.

The proprietor of Mickelson's Art Gallery, Mr. Mickelson had a reputation for independence in his artistic tastes. In a low-key way, he promoted artists he believed in whether they were fashionable or not. Sometimes they became very fashionable indeed.

This was the case with M.C. Escher, the master Dutch printmaker, whose work was almost totally unknown in the United States when Mr. Mickelson began showing it at his gallery on Seventh Street NW.

He became a recognized authority on Escher and was consulted on his art by organizations including the National Gallery of Art as well as by private collectors.

Other artists whose work Mr. Mickelson promoted included the Americans George Bellows, Jack Levine, Fairfield Porter and Philip Pearlstein.

He also showed landscapes and other studies by the noted English printmakers Anthony Gross and Norman Ackroyd and the sculptures of Milton Hebald, Peter Rockwell and Robert Cook.

Two years ago, he organized a highly praised retrospective show of the works of the late American artist Prentiss Taylor.

Mr. Mickelson was born in Washington and lived in the city all of his life. He graduated from Coolidge High School and attended American University. During World War II, he served in the Army in a combat engineers unit in Europe.

After the war, he joined his father, Samuel Mickelson, and his brother, Maurice Charles Mickelson, in Mickelson's Picture Framing, which had been started by his parents in 1912. In 1962, shortly after Samuel Mickelson's death, he added Mickelson's Gallery to the business.

Mr. Mickelson was well-known in the downtown Washington business community. He stayed in the same location through the riots that followed the death of the Rev. Dr. Martin Luther King Jr. in 1968 as well as the construction of Metro the MCI Center.

He was the president and founder of the Washington Art Gallery Association and vice president of Tifereth Israel Congregation in Washington.

Survivors include his wife of 49 years, Josephine Mickelson, of Washington; two daughters, Toby Brody of Berkeley, Calif., and Meredith Whippman of Ithaca, N.Y.; a sister, Kitty Coiner of Arlington; and five grandchildren.