Willy Ostijn (Ostyn) received his first piano lessons from Jozef Ghesquiere, son of the composer Remi Ghesquiere. From 1930 on Ostijn studied piano (Marinus de Jong) and organ (Flor Peeters) at the Lemmens Institute, where also Lodewijk Mortelmans and Staf Nees were among his teachers. During his studies Ostijn was an assistant teacher at the Lemmens Institute as well as second organist at St Rombout's Cathedral and pianist-repetiteur with the St Rombout's choir. In 1935 he graduated as a laureate and after his military service (1937) he continued his musical studies at the Conservatory of Ghent, obtaining first prizes for piano, chamber music, orchestral composition and organ (1939, Flor Peeters), in addition to the teacher diploma and an honourable mention for counterpoint (1938, Joseph Ryelandt). From 1938 to 1973 he was music teacher at the State Secondary School and the Atheneum in Roeselare. For ten years he was also piano teacher at the music school in Izegem (1939-1949).
Before World War II he formed together with Jacqueline Clarysse (violin)  and Gaston Mannes (cello) the piano trio Willy Ostijn, for whom he also often composed works of his own. During the war he started composing bigger works and in 1942 his Drie Vlaamse Dansen (Three Flemish Dances) were performed by the orchestra of Radio Broadcasting Brussels. After the war he was increasingly commissioned by the Radio Orchestra, with several creations between 1945 and 1975 even broadcast abroad. Significant conductors were Paul Douliez, Leonce Gras, Pieter Leemans, Jozef Verhelst, Fernand Terby and Ernest Maes. His accessible style can be heard in works that are still popular even today such as Pastorale for oboe an orchestra, Concert-ballade for clavier and orchestra, Romance for violin and orchestra, Beelden uit Broadway (Images from Broadway, 1950), Orkestsuite or Beelden uit Zeebrugge (Images from Zeebrugge). Starting 1961-1962 the public radio broadcast had developed a new profile within which Ostijn's orchestral style didn't fit well anymore, so he took up composing piano works, songs and works for a smaller strength. His oeuvre moreover includes overtures such as De dramatische (The Dramatic Overture), Flandria, Blijspel (Comedy) and Westland; pieces for string orchestra, a Vlaams capriccio (Flemish Capriccio) and concertante works such as Concertstuk and the Rapsodie, both for piano and orchestra. He composed organ works such as Orgelsymfonie (1939), Preludium, Elegie, a Toccata in French-romantic style and Roosvensters (Rose Windows); songs, choral works, cantatas and Masses. Finally he also wrote two operettas: Het Meisje van Damme (The Girl from Damme) and Lied der meeuwen (The Sea-gulls' Song).
© Studiecentrum voor Vlaamse Muziek - Annelies Focquaert (translation: Jo Sneppe)
 Various sources mention Catrysse as her family name, but this is not correct.