Mary Eleanor Hall, 72, a former employe of the Montgomery County public library system and a lifelong resident of Kensington, died of cancer Monday at her home in Kensington.

Mrs. Hall was an assistant in the library system from 1957 until her retirement in 1971. At the time of her death, she was president of the board of trustees of the Noyes Library in Kensington, which specializes in children's books.

She also was a member of the Community Club and for the past three years had been a member of the Women's Club of Kensington. She was a member of the Warner Memorial Presbyterian Church for more than 50 years. She also was a founder of the Kensington Historical Society.

Mrs. Hall was born in Kensington and attended schools in Washington and Montgomery County. In 1936, she married Richard C. Hall, a retired government official who now is a cabinet maker. She was a former president of the old Kensington Cooperative Nursery School.

In addition to her husband, of Kensington, survivors include a son, Donald D. Hall, of Worland, Wyo., a daughter, Elizabeth H. Sitoski, of Annapolis, a sister, Elizabeth L. Carmick, of Landrum, S.C., and two grand-daughters.

The family suggest that expressions of sympathy be in the form of contributions to the Warner Memorial Presbyterian Church in Kensington, or to the Montgomery County Unit of the American Cancer Society for the "Make Today Count" Program.