Rafael Supervia, 74, a Spanish language and literature professor at George Washington University for 25 years until his retirement in 1971, died of cancer Saturday at his home in Chevy Chase.

Prof. Supervia, who was born in Valencia, Spain, was a specialist in contemporary Spanish literature. He wrote and lectured extensively on such writers as Miguel de Unamuno and Jose Oregay Gasset. After his retirement from George Washington, he was a visiting professor at American University until his death.

Prof. Supervia was a lawyer by training. He took degrees at the universities of Valencia and Madrid and practiced law in Spain for several years.

He was a supporter of the Spanish Republic during the Spanish Civil War of the 1930s. With the victory of the Fascist forces led by Generalis-simo Francisco Franco in 1939, he fled the country to France. He moved to the Dominican Republic with the outbreak of World War II. He practiced law there and, with his wife, established a school called the Instituto Escuela."

Prof. Supervia moved to the United States in 1946 to begin his career at George Washington. He also was a founder of the Spanish Republican newspaper Democracia, which was published in New York. It is no longer in existence.

In 1977, Prof. Supervia made his first visit to Spain since he went into exile.

Survivors include his wife, Guillermina Medrano Supervia, of the home, and a daughter, Milagros Supervia, a brother, Francisco, and two grandchildren, all of Valencia, Spain.

The family suggests that expressions of sympathy be in the form of contributions to the American Cancer Society.