Born in Budapest, Sšndor studied at the Liszt Academy with both Belš Bart‹k and Zoltšn Kodšly. He remained friends with Bart‹k for the rest of the composer's life and, according to Juilliard, was one of only ten people at his funeral.
Sšndor moved to the United States in 1939, and made his Carnegie Hall debut the same year.
Along with Kodšly and Prokofiev, the works of Bart‹k were at the heart of his huge repertoire. He gave the premieres of Bart‹k's Third Piano Concerto, of the piano versions of the composer's Concerto for Orchestra and Dance Suite, and of his own transcription of his Solo Violin Sonata.
His many recordings included music of Bach, Beethoven, Chopin, Brahms, Liszt, de Falla, and Debussy, as well as the complete piano works of Prokofiev and Kodšly. In 1965, he won the Grand Prix du Disque for a complete recording of Bart‹k's piano music.
Sšndor taught at Southern Methodist University from 1956 to 1961; at the University of Michigan, where he was director of piano studies, from 1961 to 1981; and at Juilliard from 1982 until his death. He gave master classes at the Paris Conservatoire, Jerusalem Music Centre, Holland Music Sessions, and Mozarteum Salzburg. His students included Malcolm Bisson, Barbara Nissman, and H_lne Grimaud.
According to Juilliard, he judged a piano competition in Geneva three weeks ago, and taught at home until days before his death.
He was the author of On Piano Playing, which was translated into Italian, Chinese, and Polish.