John Hurford Sharon, 53, a Washington lawyer who had been active in government and civic affairs, died Tuesday at Sibley Memorial Hospital of complications from a blood disorder.

He was counsel to the Washington firm of Shaw Pittman Potts and Trowbridge from 1976 until last year when he became ill. Before that, he had been senior partner in the firm, which he formed, of Sharon, Pierson, Semmes, Crolius, and Finney for seven years.

In 1960, Mr Sharon was named by President-elect John F. Kennedy to take charge of a number of foreign policy task forces. He later was cited for his contributions to the Kennedy administration. He remained a special adviser to Mr. Kennedy until the 1963 assassination.

Mr. Sharon was born in Piedmont, Calif. He was a graduate of Princeton University and of George Washington University Law School.

After he graduated from Princeton in 1950, he came to Washington as a legislative assistant to Rep. Charles R. Howell (D-N.J.). Later he was a special assistant to the under secretary of the Army for congressional relations and in 1955-56 was administrative assistant to presidential hopeful Adlai E. Stevenson.

In 1958, Mr. Sharon became an associate of the law firm of Cleary, Gottlieb, Steen and Hamilton. In 1961-68, he was a partner in the firm of Clifford and Miller. When Clark Clifford became Secretary of defense in 1968, Mr. Sharon formed a successor firm, Sharon, Glass, Mcilwaine and Finney.

He had been associated in various capacities with Children's Hospital for many years and last year had completed a five-year term as its president. He was credited with playing a key role in raising $81 million to complete construction of the new hospital.

Mr. Sharon was a former vestryman and junior warden of All Souls Memorial Episcopal Church. Later he was a vestryman and chairman of the Columbarium Committee of St. Columba's Episcopal Church. He was a canonically licensed lay reader of the Washington Episcopal Diocese.

A resident of Chevy Chase, Mr. Sharon was active in the Chevy Chase Club, Metropolitan Club and the Princeton Club of Washington.

His first marriage to Ruth Sharon ended in divorce.

He is survived by his wife, Frances, and two sons, Barclay and Edward, all of Chevy Chase; three children by his previous marriage, Lisa, Laura and John III, all of Friendship Heights, Md; his mother, Evelyn Sharon, of Bolinas, Calif., and a brother, William, of Piedmont.

The family suggests that expressions of sympathy be in the form of contributions to the John H. Sharon Fund at Children's Hospital National Medical Center or St. Columba's Columbarium Fund.