Black Americans often meet to discuss Africa. And the African ambassadors frequently caucus. But the two groups rarely get together. Last night such a meeting, one a few called historic, took place in an ornate basement room of the Ivory Coast ambassador's residence.

"i don't recall a meeting with this kind of purpose, getting a sense of common problems, before," said Vernon Johnson, deputy assistant secretary of State for African affairs and a 26-year veteran of foregin policy. He was just one of the participants who characterized the meeting as a groundbreaking as nearly 150 persons, including the majority of the often ideologically differing ambassadors, sat on gold chairs and held a polite, frequently frank discussion on the recent Rhodesian vote, oil supplies and lobbying, among other issues.

The fireside chat, as it was called, was organized by D.C. Superior Court Judge William S. Thompson, an officer of an international law organization, Howard University Law School and the predominately black National Bar Associaton. The sponsorship of Timothee Ahoua, the Ivory Coast ambassador and ranking African diplomat in Washington, was noted by several people as a departure from the usually safe and non-nationalist Ivorian position."This is an open discussion," Ahoua told the group. "Our relations have to be strengthened. We saw Americans through the films of Clark Gable and Tarzan. You saw Africa through the films of Tarzan."

When the meeting opened Courtland Cox, one of Mayor Marion Barry's staffers and former director of a Southern Africa relief project, was first on his feet, asking about the reaction of the African nations should the United States and England lift their sanctions against Rhodesia.

Olujimi Jolaoso, the Nigerian ambassador, who was the target of kind laughter because of his country's oil power, was first to answer. He called the Rhodesian election "a fraud," and added, "We have given notice we would not accept any attempt to deal with these illegalities."

On economic development, Herschelle Challenor, the UNESCO representative in Washington, asked the ambassadors to name some priorities.

"One mistake that is often made is that aid and trade are not interlocked," said Thabo Makeka, the Lesotho envoy. "Without access to the markets what you spend (the government aid granted) can be wasted. Our priorities are to increase our living standard, produce what our people need to consume, and market the surplus."

After the 90-minute discussion, food and drinks were served, but the main points, especially the support of a cohesive lobbying effort on African issues, were strongly debated. "This is what we have all been dreaming about for years. I hope the framework can be continued," said Upper Volta Ambassador Telesphore Yaguibou. CAPTION: Picture, From Left: Timothee Ahoua, William S. Thompson, Solomon Gomez and Carl Mouttrie; by Joe Heiberger-The Washington Post