James W. Blackburn, 74, founder and president of Blackburn and Company, Inc., a media brokerage corporation, died of cancer Thursday at his home in Alexandria.

Mr. Blackburn had been president of Blackburn and Co. since its founding in 1956. The company appraised and financed radio, television and newspaper properties.

Mr. Blackburn was born in Jacksonville, Ill., and reared in Iowa. In the late 1920s, he joined the Hearst newspaper chain and worked as a salesman and advertising executive in New York City and Chicago.

He joined the Allen B. DuMont Laboratories in New York in 1939 as manager of its Broadcast Equipment Sales division.

He served in the Navy during World War II attaining the rank of commander. He was stationed in Washington where he worked in electronics research and production projects, including radar.

After the war, he became a partner in the Blackburn-Hamilton Company, a media brokerage firm, where he remained until he founding his own firm in 1956.

He was a member of St. Mary's Catholic Church in Alexandria.

His wife, Janet M. Forbes Blackburn, whom he married in 1946, died earlier this year.

Survivors include four sons, John, of Charleston, S.C., Edward, of Greenville, S.C., and James Jr. and Richard, both of Alexandria, and a sister, Margaret G. Blackburn, of Carmel, Calif.