statesman and diplomat who served as foreign minister in both the Czechoslovak émigré government in London during World War II and the postwar coalition government of Czechoslovakia.

The son of the statesman Tomáš Masaryk, Jan served in a Hungarian regiment during World War I, entered the foreign office of the newly independent Czechoslovakia in 1919, and served in Washington, D.C., and London before becoming secretary to the foreign minister Edvard Beneš in 1921. From 1925 to 1938 Masaryk was ambassador to Great Britain. During World War II he was foreign minister of the Czechoslovak émigré regime in London. A leading spokesman for that government, Masaryk made wartime broadcasts to occupied Czechoslovakia, published in English in 1944 under the title Speaking to My Country, and became a popular figure at home. Retaining the portfolio of foreign minister after his government's return to Prague in 1945, he accompanied Beneš to Moscow and also participated in the inauguration of the United Nations in San Francisco. He was convinced that Czechoslovakia must remain friendly to the Soviet Union, and he was greatly disappointed by the Soviet veto of Czechoslovak acceptance of postwar U.S. reconstruction aid under the Marshall Plan.

At the request of President Beneš, Masaryk remained at his post after the Communist takeover of Feb. 25, 1948, but a few weeks later he either committed suicide by throwing himself out of a window at the foreign office or was murdered by being thrown out.