Rudolf E. Schoenfeld, 86, retired career Foreign Service officer who had served as ambassador to Guatemala and Colombia, died Wednesday at the Cosmos Club in Washington where he had resided for 25 years. He had arteriosclerosis.

Mr. Schoenfeld retired in 1955 after serving for a year as ambassador to Colombia. He was ambassador to Guatemala from 1950 to 1953. He had been the first U.S. minister to Romania after World War II, serving there from 1947 to 1950.

During the war, when he was first secretary to the U.S. Embassy in London, Mr. Schoenfeld was designated to work with the wartime governments of Belgium, Czechoslovakia, Greece, The Netherlands, Norway, Poland and Yugoslavia as they took refuge in England.

From 1932 to 1936, he had been on duty in the Western European Division of the State Department, where he specialized in Central European affairs.

In 1955, he was lauded by President Eisenhower for his service in Romania and Guatemala. The president commented that Mr. Schoenfeld had faced with "unusual skill and courage the task of conducting relations with governments in varying degrees under Communist control."

Mr. Schoenfeld was born in Washington and graduated from Central High School, where he starred in football. He graduated from George Washington University in 1915, taught for a year at St. Albans School here and entered the Foreign Service in 1916. While serving as vice consul in Bern, Switzerland, he earned a doctorate and graduated magna cum laude from the University of Bern.

In 1946, he was political adviser to the U.S. delegation to the first session of the General Assembly of the United Nations in London.

Mr. Schoenfeld was the author of several books on such varied subjects as the early history of Maryland and taxation in Germany. In addition to the Cosmos Club, he was a member of the Metropolitan Club in Washington and the Athenaeum Club in London.

He is survived by a sister, Margaret H. Schoenfeld of Alexandria.