Kathleen Williams Kelly, 39, a former teacher at Our Lady of Victory school in Washington and Marymount High School in Arlington, died of cancer Saturday at Georgetown University Hospital.

Mrs. Kelly was the wife of Jim Kelly, an official of the Agency for International Development, and had accompanied her husband on assignments to several countries in Africa. She taught in elementary schools in Blantyre, Malawi, and in Monrovia, Liberia. In Zaire in 1972, she helped coordinate a fund-raising drive for a library, on the outskirts of Kinshasa.

She taught at Our Lady of Victory for a year in 1965 and at Marymount for a year in 1968.

Mrs. Kelly was born in Evanton, Ill. She graduated from Spring Hill College in Mobile, Ala., with honors in 1960. She did graduate work at Marquette University and was a teaching fellow there in 1962.

At the time of her death, Mrs. Kelly was a full-time graduate student at the American University school of art. She also was active in weekly discussion and prayer groups at Georgetown University.

In addition to her husband, of the home in Washington, survivors include her parents, Col. and Mrs. Bernard Williams, of San Antonio; three sisters, Elizabeth Rubin, of Rumson, N.J., Mary Williams, of Los Angeles, and Rodey MacNamara, of Manchester, Vt., and a brother, Bernard Williams Jr., of Menlo Park, Calif.