He was the chief conductor of several opera houses, and his compositions, many of them vocal music, have been performed at international festivals.
Born in Wiesbaden, Zender attended the Maifestspiele at age 13, listening to concerts conducted by Carl Schuricht, Karl Böhm and Günter Wand, among others.
From 1949, he went each year to the Darmstädter Ferienkurse, where he got to know trends in new music by Karlheinz Stockhausen, Olivier Messiaen and John Cage.
[3] Zender's opera Stephen Climax, with his own libretto based on James Joyce and Hugo Ball, was premiered on 15 June 1986 at the Oper Frankfurt, staged by Alfred Kirchner and conducted by Peter Hirsch.
[7] From 1988 until 2000, Zender taught composition at the Hochschule für Musik und Darstellende Kunst in Frankfurt.