William H. Moss, 68, the first Republican chairman of the Fairfax County Board of Supervisors and a former member of the Virginia House of Delegates, died of cancer Sunday at Circle Terrace Hospital in Alexandria.

Mr. Moss, who lived in the Franconia section of Fairfax County, was active in numerous planning and governmental agencies in Northern Virginia and the Washington area. He served on the Fairfax Board of Supervisors from 1956 to 1964 and in the House of Delegates from 1972 to 1974.

When he was named chairman of the Board of Supervisors in 1962, an editorial in The Washington Post hailed him as "a devoted partisan of close cooperation among the many jostling governments of metropolitan Washington."

Mr. Moss was a former chairman of the National Capital Regional Planning Council, the Northern Virginia Regional Planning and Economic Development Commission and the planning commission of the League of Virginia Counties. He was a president of the Northern Virginia Conservation Council and a member of the advisory board of the National Capital Transportation Agency.

He was a vice president of the Fairfax County Council of the Arts and a member of the advisory board of the Fairfax County Symphony Orchestra.

In Republican affairs, Mr. Moss was a former state vice chairman of the GOP, chairman of the party's 8th Congressional District Committee and a delegate to GOP national conventions.

Mr. Moss was born in Glenville, W. Va., and attended Glenville State College. In the 1930s, he moved to Johnstown, Pa., where he worked for the City of Johnstown and took extension courses from the University of Pittsburgh.

During World War II, he served in the Navy Construction Battalions, the "Seabees," in the Pacific. He settled in the Washington area after the war and became a title engineer for the District-Realty Title Insurance Company. He was a vice president of the firm when he retired in 1976 for reasons of health. He was a member of the Institute of Title Engineers.

Mr. Moss was a former chairman of the board of the Washington Street United Methodist Church in Alexandria, a lay speaker and a Sunday School teacher and a member of the Northern Virginia Area Methodist Board of Missions. He was a president of the Mount Vernon-Lee Little Baseball League. He also was a Mason, a Shriner, a Moose and a member of the American Legion and the Disabled American Veterans.

Survivors include his wife, Naomi, of Franconia; one son, William Hale Jr., of Alexandria; two daughters, Sonya Cockrell Parris and Jane Moss, both of Alexandria; a brother, Hall, of Cowen, W. Va.; three sisters, Maysell Luzander of Glenville, Wahneta Blair of Parkersburg, W. Va., and Marguerite Dowling of Phoenix, Ariz., and four grandchildren.