Former Rep. William Moore McCulloch, 78, a quiet Ohio Republican who became a leading champion of civil rights legislation during his 26-year career in the House of Representatives, died of pneumonia Friday at the Washington Home.

Mr. McCulloch was elected to Congress in the GOP landslide on 1946 and took his seat the following January. He served until he retired in 1973. From 1959 until the end of his career, he was the ranking Republican on the House Judicary Committee.

During these years, Mr. McCulloch became known as "Mr. Civil Rights of the GOP" and once was called "the patron saint of civil rights legislation." t

He earned these encomiums by his support of all the civil rights bills beginning with the first major one in 1957, a voting rights act. He also supported the Civil Rights bill of 1959, an anti-bombing bill in 1960, the omnibus 1964 act that desegrated public accomodations and many other aspects of American life, the tough Voting Rights Act of 1965 and the Open Housing Act of 1968.

In 1970, when that act allowed federal officials to register black southerners to vote came up for renewal, Mr. McCulloch fought efforts by the Nixon administration to weaken the measure. He accused the administration of trying to "create a remedy where there is no wrong and leaving wrong without a remedy."

In 1971, when Mr. McCulloch announced plans to retire for reasons of health, Rep. Emanuel Celler (D-N.Y.), his long-time friend and ally in the civil rights field, said it was "tragic that a man of his great competence and integrity" was forced to leave Congress.

In an interview in 1972, Mr. McCulloch said there were few votes to be won for a civil rights advocate back home in Piqua, Ohio. Asked why he had choosen to support such bills, he replied:

"Well, because there weren't many people in places where they could use their influence to implement the rights set forth in the Constitution and the decisions of the courts. I think that there are obligations on a man who is elected to Congress to try to implement some of these basic thrusts . . ."

Moreover, Mr. McCulloch said, "when I came to Congress one of the things I said . . . was that I was not going to expect my constitutents to evaluate my work by the federal dollars that I brought into the district."

When the word of Mr. McCulloch's death reached the House, Rep. Richard Bolling (D-Mo.), the chairman of the House Rules Committee and a man who also worked for the passage of th civil rights bills, said, "This country will always owe a major debt to Bill McCulloch. If it had not been for Bill McCulloch, there would have been no civil rights legislation."

Rep. Thomas Railsback (R-Ill.)m another member of the Judicary Committee, said, "Bill McCulloch, working closely with Emmanuel Celler, did more for civil rights than any member of the House."

Mr. McCulloch earned his bachelor's degree at the College of Wooster in Wooster, Ohio, in 1923. He earned his law degree at Ohio State University. He practiced law in Piqua and served six terms in the Ohio House of Representatives, including three as speaker, before being elected to Congress.

Survivors include his wife, Mabel Harris McCulloch, of Washington; two daughters, Nancy Jackson McCulloch, also of Washington, and Ann McC. Hoffman, all of Holmesville, Ohio.

The family suggests that expressions of sympathy be in the form of contributions to the William M. McCulloch Memorial Fund, c/o Elwood Penrod, Chairman of the Board, Piqua National Bank and Trust Co., Piqua, Ohio.