Charles Robert Connolly, 76 a Washington investment counselor for 50 years, died at Norfolk General Hospital in Norfolk, Va., Sunday of head injuries he sustained in a fall at ehe home of a niece.

Mr. Connolly began his career in the investment industry in Washington in the late 1920s. After World War II, he founded a firm that administered the Potomac Plan, under which investors could buy stock in the Potomac Electric Power Co. on an installment basis. The plan was discontinued in 1971.

During the war, Mr. Connolly, who held an Army reserve commission for 30 years, supervised the plan by which servicemen could buy War Bonds and GI life insurance. He was stationed in Baltimore for the three years he was on active duty. He retired from the reserves in the early 1960s with the rank of lieutenant colonel.

When the Potomac Plan was discontinued, Mr. Connolly joined the brokerage firm of William E. Lang and Co. He remained with it until his death.

He was born in Waltham, Mass., and moved to Washington when he was 17. He was a physical education teacher in the D.C. public school system before attending the U.S. Military Academy at West Point. He later attended George Washington University and Georgetown University Law School.

Mr. Connolly was a member of the University Club, the English-Speaking Union and the Retired Officers Association.

Survivors include his wife, Nina Hood Connolly, of the home in Washington; two sons, Phillip H., a retired Air Force lieutenant colonel, of Crofton, Md., and Charles R. Jr., of San Jose, Costa Rica; two brothers, Joseph, of Boston, Mass., and John Alfred, of Washington; a sister, Angela Magee, of Bethesda, and four grandchildren.