Richard Eaton, 81, who pioneered black-oriented radio programming in the United States by establishing WOOK-AM here in 1947 and was the founder of the United Broadcasting Co., died of cancer Monday at his home in Bethesda.

In addition to establishing WOOK, now called OK-100, Mr. Eaton set up the first Spanish-language radio station in Washington, the old WFAN, in 1960; the first Cuban-oriented station in Miami, WFAB-FM, and the first Japanese-language television station in Honolulu, KIKU-TV.

At the time of Mr. Eaton's death, United Broadcasting owned nine radio stations, including OK-100 in Washington and WINX in Rockville, and television stations in Manchester, N.H., and El Centro, Calif.

Mr. Eaton was best known, however, for the daily "Message of Hope" which he broadcast over his radio stations. He started the practice in 1947 and each began the same way: "Friends, to brighten your day, here is your message of hope. . . ." Mr. Eaton, who was a Quaker, spoke about religion, family, despair, love and, of course, hope. His company received hundreds of requests each year for the texts of his broadcasts. He also received numerous requests for an inspirational book he wrote, "Work Wonders Within Yourself."

A year ago, a testimonial dinner was given Mr. Eaton at the Mayflower Hotel. Among the guests were Mayor Marion Barry and the Rev. Jesse Jackson.

Mr. Eaton was born in Chicago and grew up in France. He graduated from Harvard with a degree in history and then returned to France, where he established a chain of weekly newspapers and other publications. He also wrote a collection of short stories.

With the fall of France to the Germans in 1940, Mr. Eaton returned to the United States and settled in Washington. He joined the Mutual Broadcasting System as a news commentator and held that job until 1947, when he set up his own company with WOOK.

Although he had been in effective retirement since January, Mr. Eaton remained president of the United Broadcasting Co. until his death.

His marriage to Margaret Eaton ended in divorce.

Survivors include his wife, Elsa, and their four daughters, Maude, Lucille, Alma and Modelmi, all of Bethesda; six children by his first marriage, Pierre Eaton of Rockville, Danny Eaton of Vienna, Michelle Brantell of Phoenix, Ariz., Monique Eaton of Rockville, Marguerite Bartfay of Homestead, Fla., and Francoise Gibbs of Springfield, and seven grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the American Cancer Society, 1825 Connecticut Ave. NW, Washington, D.C., 20009.