Thomas Francis O'Leary, 52, a technical information specialist with the Department of Energy, diend at Georgetown University Hospital Monday as the result of a coronary attack.

Mr. O'Leary was born in Boston and graduated from Tufts University. He also earned a master's degree in public administration at Harvard University. He joined the old Atomic Energy Commission in the early 1950s and worked in its New York City office.

In 1959, he was transferred to Washington. For some years he specialized in the foreign relations aspects of nuclear energy and served as the AEC's representative to a United Nations committee on the effects of nuclear fallout. At the time of his death, he was a technical information specialist in the Department of Energy, which absorbed the AEC and its successor agency when the department was formed earlier this year.

In World War II, Mr. O'Leary graduated from the Merchant Marine Academy at King's Point N.Y. and served in the merchant marine. He also served as a lieutenant in the Navy.

Survivors include his wife, Stella Heneghan O'Leary, of the home in Washington; and four children, Maureen, Thomas Michael, Kathleen and Nuala, also of the home, and two brothers, Paul J. and Daniel J., both of Hyde Park, N.Y.

Friends may call at Joseph Gawler's Sons, Wisconsin Avenue and Harrison Street, NW, from 7 to 9 p.m. Tuesday. A Mass will be said at the Shrine of the Most Blessed Sacrament.