Thomas P. Melady, a scholar and college president who served as a U.S. ambassador to the Vatican and was an informal liaison between Catholic leadership and top federal policymakers, died Jan. 6 at his home in Washington. He was 86.

He had brain cancer, said his wife, Margaret Badum Melady.

Dr. Melady (pronounced muh-LAY-dee) began his career in the 1950s as an authority on emerging independence movements in Africa. He served as U.S. ambassador to the African country of Burundi before becoming ambassador to Uganda in 1972, when the country was controlled by strongman Idi Amin.

In February 1973, Dr. Melady was recalled as ambassador as a signal of protest when Amin repeatedly criticized the policies of President Richard M. Nixon in Vietnam. The United States did not reopen its embassy in Uganda until 1979, after Amin had been deposed.

Dr. Melady and his wife later wrote a book about Amin that was subtitled “Hitler in Africa.”

Thomas P. Melady, U.S. ambassador to the Vatican from 1989 to 1993 and earlier to Burundi and Uganda, died Jan. 6. He was a leading authority on sub-Saharan Africa, about which he wrote several books, and a leading Catholic academic and intellectual. (Seton Hall University)

After serving as a president of Sacred Heart University in Connecticut, Dr. Melady reentered the world of diplomacy in 1989, when he was named ambassador to the Vatican by President George H.W. Bush. It was a dramatic time to be in Rome, with Pope John Paul II often cited as a prime moral force behind the collapse of the communist bloc in Eastern Europe.

“We had a major interest in seeing conversion to liberty without resorting to violence,” Dr. Melady told the Hartford Courant in 1993. We “worked very closely with the Holy See and the pope in these transitions to democracy.”

Dr. Melady was also entrusted with a secret mission at the Vatican — he was instructed to open quiet negotiations that would move the Vatican toward official recognition of the state of Israel. He worked with Jewish and Israeli representatives during his tenure as ambassador, from 1989 to 1993, and he was the direct intermediary between the president and the pope.

“In my final meeting with the pope, when I said goodbye,” Dr. Melady told Fox News in 2005, “I said I came with a mission to accomplish certain things. One thing I didn’t accomplish was a recognition of Israel. And he smiled at me and he said, ‘Wait and see.’ ”

Within a year, the Vatican recognized the state of Israel and opened full diplomatic relations.

“Ambassador Melady was very proud of his role in working with the American Jewish community to move the Vatican toward recognition of the state of Israel,” Stephen F. Schneck, director of the Institute for Policy Research & Catholic Studies at Catholic University, said Tuesday. “He was very instrumental in diplomatic efforts to help bring that about.”

Thomas Patrick Melady was born March 4, 1927, in Norwich, Conn. After serving in the Army, he became one of the first members of his family to attend college, graduating in 1950 from Duquesne University in Pittsburgh. He received a master’s degree in 1952 and a doctorate in 1954, both in political science from Catholic University.

He took an interest in independence efforts throughout Africa and in 1961 published the first of his 17 books about leaders of the growing movement. From 1959 to 1967, he was president of the New York-based Africa Service Institute, which fostered closer ties between Africa and the United States.

Dr. Melady had academic appointments at Seton Hall University in New Jersey and other colleges before he was named ambassador to Burundi in 1969.

He was executive vice president of St. Joseph’s University in Philadelphia before serving as president of Sacred Heart in Fairfield, Conn., from 1976 to 1986.

After returning from the Vatican in 1993, he taught briefly at George Washington University and published a book about his diplomatic career. He was a member of the Cathedral of St. Matthew the Apostle in Washington.

Survivors include his wife of 52 years, Margaret Badum Melady, the former president of the American University of Rome, of Washington; two daughters, Christina Melady of Paris and Monica Melady Micklos of Washington; a brother; two sisters; and seven grandchildren.

Since 2002, Dr. Melady had been affiliated with the Washington-based Institute of World Politics, where he taught a course on the art of diplomacy and continued to work “at the intersection of Catholic leadership, government and diplomacy,” Schneck said.