Olga Moore Arnold, 81, an author and former public relations specialist with the old U.S. Information Agency here, died of cancer Friday at a hospital in Laramie, Wyo., where she had been a patient for about three weeks. She lived in Washington.

Mrs. Arnold worked or the press and publications service and the office of public information at USIA from 1953 until her retirement in 1970.

She was born on a ranch near Buffalo, Wyo., and was a graduate of the University of Wyoming. She worked as a reporter and columnist on the Sheridan, Wyo., Post-Enterprise and the Denver Post before coming to Washington in about 1939, when her husband, Carl Arnold, dean of the Wyoming University Law School, was named to the legal staff of the U.S. Maritime Commission.

After his death in 1942, Mrs. Arnold worked for the Office of War Information in New York and then in London during World War II. After the war, she returned to Washington and did public relations work, lobbying, among other things, for the Smith-Mundt bill that set up USIA.

Mrs. Arnold was the author of "Windswept," a book on Wyoming, and also wrote her autobiography, "I'll Meet You in the Lobby."

She is survived by a sister, Jean Barratt of Laramie.