Hamilton Robinson, 76, a former State Department security official who also was an attorney, an investment banker, and an official of several service and cultural organizations, died at the Washington Hospital Center Oct. 12 following a heart attack.

Mr. Robinson, who was stricken at his home in Washington, was born in New Haven, Conn. He graduated from Princeton University, spent a year at Oxford University, and took a law degree at Yale University. He then went to New York City and joined the law firm of Sullivan & Cromwell.

In 1940 he moved to Washington as counsel to the British Purchasing Commission. Later in World War II, he worked for the deputy administrator of the Lend-Lease program, which provided assistance to the British. He then went on active duty in the Army and was on the staff of Gen. Brehon Somervell, commander of the Army Service Forces.

The most difficult part of Mr. Robinson's public sevice began in 1946. Leaving the Army with the rank of colonel, he joined the State Department as director of the Office of Economic Security Policy. He soon was named director of the Office of Controls, which was responsible for internal security at State.

The latter position became one of the focal points of the postwar wave of anticommunism. Conservatives criticized Mr. Robinson for what they alleged was lenience. Liberals took him to task for his role in drawing up strict security guidelines that would apply to all government agencies, civilian as well as military. For opposite reasons, both groups were critical of the way he handled personnel questions.

Although he had been a law partner of John Foster Dulles, the principal foreign policy theorist of the Republican Party and President Eisenhower's first secretary of State, Mr. Robinson was questioned about his own loyalty by some members of Congress. Such were the times that Rep. Fred Busbey (R-Ill.) queried him for 40 minutes at a public hearing about that fact that a second cousin of his had gone to Moscow in 1934 and studied Russian. This information had been put in Busbey's hands by Rep. J. Edgar Chenoweth (R-Colo.)

In 1948 Mr. Robinson left government. He was vice president and treasurer of the Foreign Service Educational Foundation, which supported the School of Advanced International Studies, now part of Johns Hopkins University, until 1952. He spent the next four years handling personal affairs. From 1956 to 1962, when he retired, he was a member of the investment banking firm of Alex Brown & Sons.

In addition to serving as president of the Columbia Hospital for Women, Mr. Robinson was an honorary director of it. He also served on the boards of the Children's Hearing and Speech Center and the Washington branch of the English-Speaking Union. He was a member of the Decatur House Property Council of the National Trust for Historic Preservation.

He was a member of the Metropolitan and Chevy Chase clubs.

His first wife, the former Elizabeth Case, died in 1940.

Survivors include his wife, Nancy B. Robinson of Washington; three children by his first marriage, Hamilton Jr. of New York City, Chalfant David of San Francisco, and Anne Robinson Righter of Boston; three children by his second marriage, Nancy Marshall Robinson Bickel of Houston, Agnes Randle Robinson of New York City, and William G.B. Robinson of Boston, and 11 grandchildren.