William C. Hill, 55, chairman of the board of Pargas Inc., a Waldorf-based distributor of liquified petroleum, died of cancer Sunday in Holy Cross Hospital.

Mr. Hill was a partner in the Washington law firm of steptoe & Johnson when he was elected executive vice president of Pargas in 1965. He became president of the company two years later and had been board chairman since 1969.

He was a member of the National Liquid petroleum Gas Association and had served as chairman of the association's committee on propane allocation and price controls. He also had been a member of the public affairs committee and had received the association's distinguished Service Award in 1977.

Mr. Hill was a native of Opelika, Ala., and served in the Army during World War II. He earned a bachelor's degree in business administration at Auburn university and was a 1949 graduate of the University of Virginia's law school.

He joined Steptoe & Johnson in 1949 and practiced tax and corporate law until joining Pargas.He lived in LaPlata.

He is survived by his wife, Rosemary, and four sons, William D. Michael S., John W., and Charles P. all of LaPlata, his mother Alma Hill, a brother, Charles, and a sister Barbara McLeod all of Alabama.