A member of the Globe Unity Orchestra, and a touring double-bass player, Kowald collaborated with a large number of European free jazz and American free-jazz players during his career, including Peter Brötzmann, Irène Schweizer, Karl Berger, Fred Anderson, Hamid Drake, Karl E. H. Seigfried, Conny Bauer, Jeffrey Morgan, Wadada Leo Smith, Günter Sommer, William Parker, Barre Phillips, Joëlle Léandre, Alfred Harth, Lauren Newton and Evan Parker. He also recorded a number of solo double-bass albums, and was a member of the London Jazz Composer's Orchestra until 1985. He also recorded a number of pioneering double bass duets with Maarten Altena, Barry Guy, Joëlle Léandre, Barre Phillips, William Parker, Damon Smith and Peter Jacquemyn.
In addition, Kowald collaborated extensively with poets and artists and with the dancers Gerlinde Lambeck, Anne Martin (formerly of Pina Bausch Ensemble), Tadashi Endo, Patricia Parker (founder of the Vision Festival), Maria Mitchell, Sally Silvers, Cheryl Banks (formerly of Sun Ra's Arkestra), Arnette de Mille, Sayonara Pereira, and Kazuo Ohno. Specific works included Die Klage der Kaiserin (1989) with Pina Bausch, short pieces (since 1989) with Jean Sasportes, The spirit of adventure (1990) with Anastasia Lyra, Wasser in der Hand (1990/91) with Christine Brunel, and Futan no sentaku/The burden of choice (1990/91) with Min Tanaka and Butch Morris.
Besides his duo work with singers such as Jeanne Lee, Diamanda Galás, Anna Homler or Sainkho Namtchylak, Peter was especially interested in his international improvising ensemble Global Village with musicians from different cultural regions of the world: China, Japan, Near East, South Europe, North and South America.
He died of a heart attack in New York City in 2002.
- 1966 Alexander Schlippenbach: Globe Unity
- 1967: Peter Brotzmann: For Adolphe Sax
- 1968: The Peter Brotzmann Octet: Machine Gun
- 1973: Globe Unity Orchestra - Live in Wuppertal
- 1979: Leo Smith/Kowald/Sommer: Touch the Earth
- 1986: Global Village Suite
- 1987: Bill Dixon: Thoughts (Soul Note)
- 1996/2003: Duos 1 / Duos 2
- 1998: Fred Anderson Trio - Live at the Velvet Lounge
- 2003: Global Village