Dr. Harold E. Pendleton, 59, an official of the American Petroleum Institute who had been an area resident since about 1970, died of cancer Sunday in Jefferson Memorial Hospital in Alexandria. He lived in Sterling, Va.

Dr. Pendleton was a native of Granite City, Ill. He graduated from the University of Illinois, where he was a member of Phi Beta Kappa. He earned a master's degree in English at Harvard Univeristy and a doctorate in English and philology at Illinois.

He taught at Illinois and at the Pan American College in Texas. In the late 1950s, he moved to Michigan to work in the automobile industry and was a speech writer for Ford and Chrysler.

In 1963, Dr. Pendleton joined the API in New Jersey as a senior speech writer. He later transferred to the institute's Washington office and was assistant director of its environmental affairs department at the time of his death.

Dr. Pendleton served aboard destroyers with the Navy during World War II.

Survivors include his wife, Hilda, of Sterling; a daughter, Michaelle Flowers of Alexandria; four sons, Christopher, of Elizabeth, N.J., James, of Springfield, Va., Martin, of Burke, Va., and Army Spec. 4 Donald, of Fort Belvoir; two sisters, Dorothy Starr of Mobile, Ala., and Harriet Juda of Granite City, Ill., and three grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the American Cancer Society.