Born in 1947 in Warsaw, he studied sound engineering and composition with Tadeusz Baird, Andrzej Dobrowolski and Włodzi mierz Kotoński at the Fryderyk Chopin State High School of  Music in Warsaw. He took part in the Courses on the Applications  of Mathematics organised by the Polish Academy of Sciences in  Warsaw (1974) and in the Summer Courses for New Music  in Darmstadt (1974 and 1976). He cooperated with the Polish  Radio Experimental Studio (from 1973) and worked at the Center  for the Creative and Performing Arts at the State University of  New York at Buffalo. Knittel has composed orchestral, choral  and chamber music, operas and ballets, performed numerous  electroacoustic and computer works, and created sound installations. He has appeared as a composer and performer throughout Europe as well as in Asia and the Americas. His discography  comprises more than 60 albums. He was a cofounder of several  improvised music ensembles, including KEW Composers’ Group  (1973–75), Independent Electroacoustic Music Studio (1982–84),  Freight Train (1986–2017), European Improvisation Orchestra  (1996–98), CH&K&K Trio (1999–), and Mud Cavaliers (2003–). In 1981 he cooperated with the Culture Committee of So li darność, Mazovia region, and was a member of independent culture circles during Martial Law in Poland. In 1989–92 he was  Vice-President of the Polish Society for Contemporary Music,  and cocreated the Audio-Art festival at the Ujazdowski Castle  Centre of Contemporary Art. He served as Director of the Warsaw Autumn Festival (1995–98), President of the Polish Composers’ Union (1999–2003), Vice-President (2000–5) and President  (2005–17) of the Polish Music Council, as well as member of  the Board of the European Music Council (2014–18). In 2003–6  he was a member of TVP’s (Polish state television) Supervisory Board, in 2004–10 – member of the Programme Board of  the Zachęta National Gallery of Art, in 2006–22, member of Society of Authors ZAiKS. In 2006 he founded the Ad Libitum International Festival of Improvised Music. He is a retired professor  of the Chopin University of Music, and has lectured at the music  academies of Łódź and Cracow. As a musical journalist, Knittel  has contributed to such magazines as Tygodnik Literacki, Ruch  Muzyczny, Studio music magazine, as well as TVP’s classical  music department and Pegaz TV programme.

He is an honorary member of the Polish Society of Electroacoustic Music. His accolades include the Solidarity Award for Music  (1985), Polish Composers’ Union Award and Cyprian Norwid  Prize (2003), Gloria Artis Silver Medal of Merit to Culture (2005),  Gold Medal for Guardians of National Remembrance Sites  (2005), For Merit to Polish Culture award (2010), SPAM Medal  For Merit to Polish Music (2010), Medal of the KEN National  Education Committee (2011), a grant from the Foundation for  Contemporary Performance Arts in New York (1998), Gustav  Mahler Composition Prize (2017), Theatre Award of the City of Gdańsk (2017), ZAiKS Centenary Award (2019), and Gloria Artis  Gold Medal of Merit to Culture (2025). 

Selected works (since 2000): Out of the Depths Have I Cried  unto Thee, O Lord… to psalm texts (2000), Sonatas da camera  nos. 8–20 for various performers (2000–16), El maale rahamim…  for mixed choir and symphony orchestra (2001), Norwid Songs  for soprano and piano (2001), Der Zirkus ist gekommen for  soprano, female dancer, flute, cello, piano, prepared piano and  electronics (2003), V2R Trio (Grand River Trio) for clarinet,  violin, piano and electronics (2003), To Touch a Snake From  the Inside, touch-and-sound installation (2003), The Passion of  Our Lord according to St Matthew for voices, mixed choir, two  percussion players, string orchestra and electronics (2004),  A Memoir from the Warsaw Uprising for five actors, female choir,  piano, cello, symphony orchestra and electronics, to words by  Miron Białoszewski (2004), Concerto for Harpsichord and  Orchestra (2004), …in the opposite direction…, electroacoustic  music (2004), Social / Anti-Social, performance and video installation (2005), Vagante for soloists, orchestra and tape (2005),  Toccata for symphony orchestra (2007), Snatches of Memory II  for two pianos, electronics and video (2007), Cheap Imitations,  chamber music for flute, clarinet, piano, string quartet and tape  (2008), The Four Seasons, sound installation (2008), Chopin  Air, sound installation (2010), free for Windows for guitar and  electronics (2011), Meetings (in Two Unfinished Acts), music for  the Polish Dance Theatre and Grand Theatre in Łódź (2011), Partita 1 (Koori) for saxophone, symphony orchestra and electronics  (2013), Partita II (Inuit) for flute, string orchestra and electronics (2013), AD-W2014 for actor, improvising soloists, orchestra and choir (2014), The Last Judgement, opera to a libretto by  Mirosław Bujko (2017), Like a Stone for improvising soloists and  choir (2017), free for(m) macwin nos. 1–3, electroacoustic music  (2011–18), Oneg Szabat for flute, violin, cello, amateur choir,  video and electronics (2019), Canticum profugorum, oratorio for  voices, instruments, choir, children’s choir, orchestra and electronics to words by Tadeusz Sławek (2020, rev. 2022), Voices for  four actors, chamber choir, chamber orchestra and electronics, to  words by Jan Polkowski (2021), Concert at Przyczółek Grochowski  (2021), Maurycy Beniowski. An Alternative Children to words by  Maciej Wojtyszko (2022), untitled 001–023, untitled 024–044, electroacoustic music (2022), It’s just a feedback, electroacoustic  music (2023), Gdańsk Nostalgia for carillon (2024), 4:15, song  from the Warsaw Autumn Songs cycle for the hańba ensemble,  to words by Grzegorz Uzdański (2024), Ka makana o ke ola for  string orchestra (2025), Baroque Sonata AH200 for string quartet  and harpsichord (2025), Painted with Moonlight to old Japanese  haiku translated by Cze sław Miłosz, for vocal sextet and electronics (2025), forMIA for improvised violin, percussion, electronics  and chamber orchestra (2026).