Ernst Křenek (krĕ´nĕk, Czech kerzhĕ´nĕk), 1900–1991, Austrian-American composer, b. Vienna. to Czech parents. He studied in Vienna and Berlin, and in the early 1920s he composed chamber music, a violin concerto (1924), and two operas, in a neoclassical style. In 1925 he became conductor at the opera house in Kassel. His jazz opera Johnny Strikes Up (1926), was extremely successful and has been translated into many languages. He returned to Vienna in 1928, and after a brief period of neo-Romanticism, during which he wrote the opera Leben des Orest (1930) and a Schubertian song cycle, he gradually adopted the twelve-tone technique (see serial music) originated by Arnold Schoenberg. His opera Karl V (1933) is entirely in the twelve-tone system. In 1937, Křenek moved to the United States, where became a citizen (1945). There he taught and composed chamber, orchestral, and choral music and wrote the operas Tarquin (1940) and Sardakai (1969) and the chamber opera Dark Waters (1950). He composed Eleven Transparencies (1956) for orchestra and electronic music. Křenek was also known as lecturer, pianist, and the author of Studies in Counterpoint (1940), Self-Analysis (1950), excerpts from an unpublished autobiography, and Exploring Music (tr. 1966).