Retired Army Col. Charles Weller McCarthy, 78, a staff officer who served at truce negotiations at Panmunjum, Korea, in 1952, and who later served at the Pentagon, died Thursday at the Wisconsin Avenue Nursing Home after a stroke. He lived in Chevy Chase.

A native of Prescott, Ontario, Col. McCarthy grew up there and in Washington. He attended St. John's College High School and Catholic University.

In 1926, he was commissioned as an infantry officer. His staff assignments included tours with the old War Department, where he was first secretary to the State, War and Navy Coordinating Committee, a parent organization of the National Security Council. During World War II, he represented the War Department at the Council of Foreign Ministers meeting in Moscow.

From 1948 to 1951, he was senior military attache in the U.S. Embassy in Chile. He then became senior liaison officer at the negotiations at Panmunjum, Korea. The negotiations led to the end of the Korean conflict. Before retiring in 1956, he spent several years stationed in Washington.

Col. McCarthy's military decorations include the Distinguished Service Medal, the Legion of Merit, the Bronze Star.

He and his first wife, the late Charolette Piekenbrock McCarthy, reared four children. He married the former Helen Marie Sheerin in 1963.

Col. McCarthy was active in Georgetown Visitation Convent and School affairs and attended Little Flower Catholic Church in Bethesda.

Besides his wife, of Chevy Chase, survivors include a daughter, Jude Howard of Potomac; a son, Army Maj. Charles Peter McCarthy of Fairfax, and 10 grandchildren. Two other sons, both Army officers, predeceased him. Thomas W. was killed in action in Vietnam in 1964 and John M. Died last year.

The family suggests that expressions of sympathy be in the form of contributions to the charity of one's choice.