John J. Slattery Sr., 86, president of Slattery's Radio and Television Co. Inc. here, which he founded in 1934, died Wednesday at Sibley Memorial Hospital after a heart attack.

A lifelong resident of Washington, he was a graduate of Immaculate Conception High School and Catholic University. During World War I, he was an officer in the Army Motor Transport Corps.

Before founding the radio company, he was head of Slattery Iron Works, which he had started in the 1920s. His company installed structural steel in the New House Office Building, the Investment Building and helped install the first elevator in the Washington Monument.

Mr. Slattery was active in many Catholic and civic organizations. He was a member of St. Ann's Catholic Church, the Holy Name Society and the St. Vincent de Paul Society. He was a former president of the Catholic Youth Organization (CYP) here and belonged to the Knights of Columbus Washington Council.

He was a former president and member of the board of directors of the Friendship Lions Club and served as the Lions Tail Twister. He had been active in the affairs of the Washington Home.

Survivors include his wife of 56 years, the former Agnes Harrington, of Washington; two sons, John Joseph Jr. and Frank Joseph, both of Washington; seven brothers and sisters, Catherine S. Thyson, Mary S. Cain, Daniel J., and Nora S. Turvey, all of Washington, Helen S. Dawson of Canton, Mass., Loretta S. W. Wilson of Gaithersburg, and Francis J., of North Carolina, seven granchildren and one great-grandchild.