H. Mason Neely, 38, a member of the D.C. Public Service Commission from 1971 to 1977 and a Washington attorney, died Thursday at the Washington Hospital Center of a seizure disorder associated with cirrhosis of the liver. He had been stricken at his home in Washington.

Mr. Neely, who was active in Republican politics in the District, was appointed to the commission by President Nixon in 1971. The commission regulates public utilities, the taxicab industry and some other businesses that serve the public. He was appointed to a second term on the three-member body in 1974 and continued to serve until that term expired in 1977.

A native of Washington, Mr. Neely was a graduate of Roosevelt High School. He graduated from Morgan State University in Baltimore and later worked as a deputy U.S. marshal and as a D.C. policeman.

He earned a law degree at Howard University in 1966 and entered a private law practice in Washington a year later.He resumed his law practice after finishing his term on the Public Service Commission.

Mr. Neely was a member of the Peoples Congregational Church, the D.C. and American bar associations, the Association of Regulatory Commissioners and the D.C. Institute of Mental Health. He also was a member of the Metropolitan Police Boys Club, the Jack and Jill Club of America and the Pershing Rifle Association, an ROTC unit at Morgan State.

Survivors include his wife, Elsie, and two sons, Allen and Frank, all of Washington.