The Rev. Dr. Lester Clark Lewis, 75, minister emeritus of All Souls' Unitarian Church, and a research physicist, died of cancer Monday at his home in Washington.

He was recalled to the ministry at All Souls' in 1965, and was minister in charge of senior members until his retirement in 1971.

Born in Lynn, Mass., Dr. Lewis grew up in Wakefield, Mass. He earned a bachelor's degree in physics from Massachsuetts Institute of Technology in 1922.

He later worked for the research laboratory of the General Electric Co. in Schenectady, N.Y., and earned a master's degree in chemistry from Union College.

He went on to earn a doctorate from the Molecular Beam Institute of the University of Hamburg in Germany in 1931.

Dr. Lewis then was chief physicist at the research laboratory of the Mead Corp. in Chillicothe, Ohio, for seven years.

In 1939-40, he was a physicist in the textile foundation of the National Bureau of Standards here. During the early part of World War II, he was in the radiation laboratory at MIT.

Dr. Lewis also studied at Harvard University Theological School, where he received a bachelor of sacred theology degree in 1944.

He then held Unitarian ministries in Lexington, Mass., Brockton, Mass. and New Haven, Conn., until he became head of the physics and mathematics department of Wagner College on Staten Island, in 1956.

Dr. Lewis later spent a year as curator of science and technology at the Smithsonian Institution before returning to the ministry.

He had served on the Unitarian Service Committee, the Adult Education Committee and the International Association for Liberal Religion. He had been on numerous Star Island (N.H.) commissions of the Unitarian denomination and had helped found its international affairs committee.

Dr. Lewis was an active member of the Optical Society, the World Future Society, the Society of Stereo-photographers, the Forum for Professionals and Executives of the Washington School of Psychiatry and the Washington Area Ministers Association.

As minister emeritus at All Souls', he continued to be active with the Friendly Seniors and also to perform weddings and christenings.

He is survived by his wife, Helen, of the home; a son, Warren Frank, of Astoria, N.Y.; two daughters, Constance Fenton, of San Rafael Calif., and Sara Young, of Oxon Hill; two sisters, Edith Mayne, of San Diego, Calif. and Dorris Brackley, of Londonderry, N.H., and nine grandchildren.

The family suggests that expressions of sympathy may be in the form of contributions to the Lester Lewis Memorial Fund for the Senior Members Committee of All Souls' Church.