Malissa Childs Elliott, 50, an author and a former Soviet specialist for the State Department and U.S. Information Agency, died of a brain tumor Tuesday at the Mary Hitchcock Memorial Hospital in Hanover, N.H.

Mrs. Elliott was born in St. Louis and grew up there and in Washington after her father, Marquis Childs, a syndicated columnist, moved here. She attended the Yale University Drama School and was a Phi Beta Kappa graduate of Stanford University, where she studied the Russian language and Soviet affairs.

She worked on Soviet affairs in the State Department from 1950 to 1953, and then worked briefly at the Library of Congress. From 1962 to 1968, she worked at USIA, now the International Communication Agency, as an editor on Amerika, a magazing that is distributed in the Soviet Union, and on an Arabic language magazine. In connection with the Arabic publication she traveled to Arab countries and met leaders of women's groups.

Before joining USIA, Mrs. Elliott had been on the editorial staffs of Fortune Magazine and the New York Times Sunday Magazine in New York. In recent years she had lived in Springfield, Vt.

She wrote two novels, "The Country of Love" and "Game of Chance with Strangers." Her most recent book, "Scenes from Country Life," is about her impressions of Vermont after living in New York and Washington. It is scheduled for publication this spring.

Her marriage to Marine Col. H. J. Redfield ended in divorce. She published under the name Malissa Redfield.

Survivors include her second husband, Robert Irwin Elliott, of the home, her father, of Washington, and a brother, Prentiss Childs, of Santa Fe, N.M.

The family suggests that expressions of sympathy be in the form of contributions to The Hitchcock Foundation, c/o Mary Hitchcock Memorial Hospital, Hanover, N.H., 03755.