James Preston Kem (April 2, 1890 – February 24, 1965) was an American politician representing Missouri in the United States Senate from 1947 to 1953.

Kem defeated incumbent Frank P. Briggs, who had been appointed to the office in 1945 when Harry S. Truman resigned to become vice president.

During his one term in the Senate, Kem was a staunch opponent of President Truman, characterizing him as a puppet of Tom Pendergast's corrupt political machine in Kansas City.

Kem lost his re-election bid in 1952 to Democratic candidate, Stuart Symington, a former Emerson Electric CEO who had been United States Secretary of the Air Force in the Truman administration.

Kem retired to a Washington, D.C. law practice and then raised Angus cattle in Virginia until his death in 1965 at the age of 74.