William John Hickey, 66, a lawyer who specialized in labor and transportation law and a lifelong resident of the Washington area, died of cardiac arrest Thursday at his home in Kensington.

Mr. Hickey was born in Washington and graduated from the old Central High School After graduating from Brown University in 1937, he returned here and joined the Office of the Comptroller of the Currency in the Treasury Department as an assistant national bank examiner.

During World War II, Mr. Hickey worked in the Office of the Alien Property Custodian and then was commissioned in the Navy, where he was cost inspector. He continued this work in the Navy Department after leaving the service. In 1948, he earned his law degree at Georgetown University.

In that year, Mr. Hickey joined the Justice Department as an attorney. He specilized in litigation arising from regulatory orders concerning transportation. In 1954, he left the government and was named vice president and general counsel of the American Short Line Railroad Association, a trade organization. He held that position until 1963. The following year, Mr. Hickey went into a general law practice in Washington in which he specialized in transportation and labor matters. He remained in practice until his death.

Mr. Hickey was a member of the D.C. and American bar associations and was admitted to the bar of the U.S. Supreme Court.

Survivors include his wife, Elizabeth M., of Kensington; three children, Florence E. Biddle of Vienna, William J., Jr., of Medway, Mass., and Robert J. E., of Alexandria, and six grandchildren.