Thomas F. Wert Sr., 76, a retired lieutenant in the guard force at the National Gallery of Art and a veteran of World War II and the Korean conflict, died of cardio-respiratory arrest Tuesday at the Fairfax Nursing Center in Fairfax. He had been in a hospital and then in the Fairfax facility since suffering a stroke last September.

Mr. Wert was born in Springfield, Mo., and grew up in Washington. He was a milk wagon driver for the Chestnut Farms Dairy and then worked in a warehouse.

During World War II, he served in the Army in the Pacific and later in the occupation of Germany. After the war, he returned to the warehouse business. He was recalled to active military duty during the Korean conflict and served in the war until he was released from the service in 1952.

Mr. Wert, who lived in Temple Hills, began his career as a quard at the National Gallery in the same year.He was a lieutenant when he retired in 1971 for reasons of health.

He was a past-commander of American Legion Post No. 41 at the Department of Justice. He also had been financial secretary of Local 1381 of the American Federation of Government Employees.

His marriage to the former Dorothy Scharf ended in divorce. His second wife, Alina Wert, died last year.

Survivors include two children by his first marriage, Thomas F. Jr., of Longwood, Fla, and Dorothy M. Walters of Fairfax, nine grandchildren and 10 great-grandchildren.

The family suggest that expressions of sympathy be in the form of contributions to the American Heart Association.