Composer and pianist. He studied composition with his father Kazimierz Sikorski (graduating with honours) and piano with Zbigniew Drzewiecki at Warsaw’s State High School of Music (1956–62).
In 1961–63 he worked at the Polish Radio Experimental Studio; then in 1963–68 he taught instrumentation and score reading at the Faculty of Composition, Conducting and Music Theory of his Warsaw’s State High School of Music.
Having received an honourable mention at the Polish Composers’ Union’s Youth Competition in 1962, he made his Warsaw Autumn debut a year later with Antiphons (1963). From that time onwards his works were presented at the festival almost every year.
In 1965–66 he stayed in Paris on a French government scholarship; in 1975–76 a US government scholarship from the Senior Fulbright Program took him to New York, where (at the Columbia-Princeton Electronic Music Center) he produced his Solitude of Sounds for tape (1975).
Sikorski was a member of the Polish Composers’ Union from 1964, member of the Union Board in 1973–75, and of the Warsaw Autumn Repertoire Committee in 1966–74 (1973–74 as its chairman).
He was also active as a pianist. In 1963–67 he collaborated with Music Workshop ensemble (including Zygmunt Krauze), and from 1967 until the mid-1970s with Ad Novum (including Zbigniew Rudziński).
He also performed his own works at concerts in Stockholm, Athens, Brussels, the United States, and Japan.
Selected works: Two Preludes for piano (1955), Song of Wit Stwosz for soprano, soprano choir and chamber orchestra (1956), Echoes II for 1–4 pianos, bells, two gongs, two tam-tams, percussion and tape (1961–63), Antiphons for soprano, piano, horn, bells, two gongs, two tam-tams and tape (1963), Prologues for female choir, two pianos, four flutes, four horns and three percussionists (1964), Concerto breve for piano, 24 brass and four percussionists (1965), Monody and Sequence for flute and piano (1966), Sequenza I for orchestra (1966), Sonant for piano (1967), Intersections for four percussionists (1968), Diaphony for two pianos (1969), Homophony for 12 brass instruments, piano and gong (1970), For Strings for three violins and three violas (1970), Absent-Minded Window-Gazing for piano (1971), Vox humana for mixed choir, two pianos, 12 brass, four gongs and four tamtams (1971), The Adventures of Sinbad the Sailor, radio opera for soprano, tenor, six reciting voices, female choir, and orchestra (1971–72), Holzwege for symphony orchestra (1972), Untitledfor piano and three instruments (1972), Hearkening Music for two pianos (1973), Music from Afar for mixed choir and instruments (1974), Other Voices for 24 winds, four gongs and bells (1975), Solitude of Sounds for tape (1975), Sickness unto Death for reciting voice, two pianos, four trumpets and four horns (1976), Music in Twilight for piano and orchestra (1977–78), Hymnos for piano (1979), Strings in the Earth for 15 strings (1979–80), Monophony for orchestra (1979–80), Autograph for piano (1980), Modus for trombone (1980; rev. for cello, 1982), Afar a Bird for clavichord, tape and reciting voice (1981), Paesaggio d’invernofor strings (1982), Euphony for piano (1982), Autoritratto for two pianos and orchestra (1983), Recitativo ed Aria for string orchestra (1983), Rondo for harpsichord (1984), La notte – Omaggio a Friedrich Nietzsche for string orchestra (1984), Das Schweigen der Sirenen (nach Kafka) for cello (1986–87), Diario 87 for tape and reciting voice (1987), Omaggio per quattro pianoforti ed orchestra in memoriam Jorge Luis Borges (1987).