- Klavierstück III, Nr 2/III (1952-55)piano
- Klavierstück IV, Nr 2/IV (1952-55)piano
- Klavierstück IX, Nr 4/I (1954-55)piano
- Klavierstück V, Nr 4/II (1954-55)piano
- Klavierstück VII, Nr 4/III (1954-55)piano
- Klavierstück VIII, Nr 4/IV (1954-55)piano
- Klavierstück X, Nr 4/V (1961)piano
- Klavierstück XI, Nr 7 (1956)piano
- Klavierstück XII, Nr 49 3/4 (1979, 83)piano
- Klavierstück XIII, Nr 51 1/2 (1981)piano
- Klavierstück XIV, Nr 57 2/3 (1984)piano
- Ko Amar (Thus Said) (2008-10, 14)Cycle: Mishpatim (Laws)
- Kol Nidre (1996), 8:00string quartet
- Konna yume wo mita [I Saw a Dream Like This] (2003, 10), 12:00violin, cello and piano
- Kontakion (1969)flute, oboe, clarinet, bassoon, horn, piano, 2 violins, viola, cello and double bass
- Kontakte, Nr 12 1/2 [mixed version] (1958-60), 35:00piano, percussion and 4-channel fixed medium
- Kopernikus (1978-79), 67:002 sopranos, mezzo-soprano, tenor, baritone, bass, oboe, 3 clarinets, trumpet, trombone, violin and stereo fixed medium
- Korwar (un clavecin au zoo) (1972)harpsichord and fixed medium
- Kosalia Arini (1969), 12:00gamelan gong kebyar
- Krasch! (1993)saxophone quartet, percussion ensemble and fixed medium
- Kreasi Baru (2018)
- Kreuzspiel, Nr 1/7 (1951)oboe, bass clarinet, piano and 3 percussions
- Kryptogramma (1970)6 percussions
- Kubla Khan: dirge-refrains (Tombeau de Vivier) (1989), 15:00chamber orchestra (16 musicians)
- flute, oboe, clarinet, horn and bassoon
- Kya (1959), 19:00clarinet in C and small ensemble
