Jesse J. Warr Jr., 56, leader of the fight for equal education in Prince George's County during the bitter desegregation era who rose to become the county's first black school board chairman, died yesterday morning after he was stricken at his home with a heart attack.

A chemist by training, Mr. Warr entered the politics of the county school system because he felt the black children of the county were not receiving an equal opportunity in education. His determination to do something about it led him to remain the only black on the school board for nine years.

In his position Mr. Warr was often subjected to subtle and not-so-subtle racial slurs. But his optimism and patience eventually won over his severest critics, and he believed, brought new opportunities to the black youth of the county.

"He was extremely religious . . . and that faith made him the way he was. He never gave up on anyone," school board member Maureen K. Steinecke said yesterday.

County Executive Winfield M. Kelly Jr., who opposed Mr. Warr during the battle that led to the 1972 order to use busing to desegregate the county's schools, said yesterday that Mr. Warr's loss will be an "almost impossible" void to fill.

A Memphis native who never lost his soft Tennessee accent, Mr. Warr came to Washington after graduating from LeMoyne College in his hometown. Until his retirement in 1974, he had worked as a chemist for the U.S. Geological Survey.

He did graduate work at Howard University and earned a master's degree in teaching last year at Trinity College of Washington. He was planning to use those new skills, which he joined as a teacher of geosciences after his retirement in 1974.

Mr. Warr's first entry into the explosive desegregation issue came, ironically, in the form of an inquiry as a concerned Prince George's County parent who was hoping to find some way to end the long-distance busing of black children past white schools.

That was in the days when the county still had blacks-only schools despite the 1954 U.S. Supreme Court decision banning segregated schools.

A member of county's NAACP, as well as a Republican and leader in the Episcopalian Church of the Atonement in Washington, Mr. Warr was appointed to the county school board in 1968 by then-Gov. Spiro T. Agnew.

Before his first term was over, Mr. Warr had joined other county parents with the NAACP and the ACLU in filing suit against his own county school system in order to bring about equal education.

That produced the 1972 court order that brought busing to the county in 1973. Desegration was completed by 1975, without the violence that so tarnished other attempts throughout the country.

It was Mr. Warr who received much of the credit for the smooth transition. But it was not until three years later that he felt the bitterness had ended.

At the time of his nomination for school board chairman, Mr. Warr uncharacteristically took a bow for his efforts of a decade: "My nomination as the first black chairman . . . proves, to a degree, that the stand I took on desegregation, my thrust for equal opportunities for all students, has been vindicated.

He won unanimously in the 1976 election, the first chairman to win the votes of all his or her fellow board members.

Normally, Mr. Warr watched while his opponents on the board grabbed for publicity. During a particularly raucous meeting in which he lost a number of programs dear to his black constituents, Mr. Warr, undaunted, laughed at the proceedings and said he would start charging admission price to watch the circus.

Later, as chairman, Mr. Warr won the passage of these same programs and brought together a board that previously had been divided by the racial and community fears that clouded the years of busing.

He brought with him as vice chairman Norman Saunders, one of the most vocal opponents of busing and a man won over by what he described as Mr. Warr's "very rare warmth of personality."

All the while, as Mr. Warr kept up his active role in the NAACP, the ACLU and the Coalition for the Handicapped, he was the board member who was most frequently seen visiting local county schools. Fairmont Heights High School, the former black majority school, was the school for which Mr. Warr had a special affection, and he frequently visited it to see that the students were thriving.

As chairman, he consciously spoke of bringing better education to all children, and School Supt. Edward J. Feeney yesterday remembered him as a man whose humanity transcended race politics or a particular point of view.

Mr. Warr is survived by his wife, Lucy, of the home in Landover, five children, three brothers and a sister.