William C. Thompson, 78, a retired Chevy Chase building contractor, died Friday at the Manor Care Nursing Home in Wheaton. He had cancer.

Mr. Thompson was born in Irvington, va. He moved to Montgomery County in the mid 1920s. He worked in the accounting department of the Hecht Company department store in Washington for several years before World War II, in which he was commissioned a lieutenant in the old Army Air Corps in this country.

Mr. Thompson left the service in 1943 and settled in Chevy Chase, where he established a contracting firm. He designed and built homes in this area until 1955, when he moved to Sarasota, Fla. Mr. Thompson maintained a similar firm there until 1963.

He returned to Chevy Chase and reestablished his contracting business. He worked there until his retirement last year.

Mr. Thompson was a Mason, a Shriner, and member of New Jerusalem Lodge No. 9 in Washington.

He was also a member of the Kensington Baptist Church.

Survivors include his wife, Emma G., of Chevy Chase; a daughter, Patricia A. Dube of Somerset, Mass,; a son, Frank R., of Silver Spring; two sisters, Marie T. Smith of Potomac, Virginia F. Thompson of Silver Spring, and four grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the Montgomery County Chapter of the American Cancer Society.