Robert L. Moran, 64, the business representative for Painters Council 51 of the Brotherhood of Painters and Allied Trades and a union member for 37 years, died of cancer Thursday at Calvert Memorial Hospital in Prince Frederick, Md.

Mr. Moran, who was born in Hampton, Va., grew up in Washington and graduated from Gonzaga High School. He began working as a plumber's apprentice, but at about the age of 21 switched to painting. He followed that trade for the rest of his life.

He was a member of Local 1773 of the Painters Union. In the course of his career, he held several union posts as well as working as a painter. He had been business representative for District Council 51 for the past two years. At the time of his death, he also was treasurer of his local and secretary-treasurer of the Brotherhood Conference of Maryland, Virginia, the District of Columbia and Delaware.

Mr. Moran lived in Langley Park until about 10 years ago, when he went to work on the Calvert Cliffs nuclear power plant and moved to Long Beach, Md. He was a member of Our Lady Star-of-the-Sea Catholic church in Solomons Island, Md.

Survivors include his wife, Elizabeth Collis Moran, and a daughter, Martha G. Moore, both of Long Beach, and three grandsons.

The family suggests that expressions of sympathy be in the form of contributions to the New Building Project, Calvert Memorial Hospital, Prince Frederick, Md.