Sister M. Ann Elizabeth, 84, a member of the Congregation of the Sisters of the Holy Cross and a retired chemistry professor at the Dunbarton College of the Holy Cross in Washington, died at St. Angela Hall in Kensington June 22 of a heart ailment and rheumatoid arthritis.

Sister Ann Elizabeth taught at Dunbarton from 1941 to 1973, when she retired. She also had served as academic dean, faculty chairman, and chairman of the chemistry department at Dunbarton.

She was an authority on the reactions of hydrocarbons in the field of an electric discharge and in radioisotope research technique in general.

From 1974 until 1980, she was a volunteer research analyst with the National Advisory Council on Vocational Education in Washington.

Born Mary Catherine Waters in Washington, she earned bachelor's and master's degrees at Notre Dame University and a doctorate in chemistry at Catholic University. She also studied the history and philosophy of science at Cambridge University in England.

She taught at St. Cecilia's Academy in Washington from 1919 to 1926, and at other institutions in Utah and Illinois, before joining the Dunbarton faculty.

She was a fellow of the American Institute of Chemistry and a member of the American Chemical Society. Sister Ann Elizabeth received awards from the Association for Higher Education, the old Atomic Energy Commission and the National Science Foundation. She was featured in a network television program on chemistry professors.

Survivors include a sister, Anne M. Granados of California, Md.