Jan Koetsier was born on 14 August in Amsterdam. His parents were the singer Jeanne Koetsier and the teacher Jan Koetsier-Muller.

The family moved to Berlin, where Jeanne Koetsier had been awarded a scholarship to study singing. Jan Koetsier-Muller worked in Berlin as a language coach for actors, including teaching at the Acting School of the Deutsches Theater.

Studied at the Hochschule für Musik in Berlin, beginning in Waldemar Lütschg’s piano class. He quickly decided to change to conducting, and studied with Walther Gmeindl (score reading and music theory) in preparation for the entrance examination. He studied conducting with Julius Prüwer from 1932-33 and also took clarinet lessons with his fellow student Harald Genzmer. Decisive influences on Koetsier’s career as composer and conductor were his friendships with Artur Schnabel, who taught at the Hochschule, and with the pianist Leonard Shure and the composer Siegfried Borris.

Répétiteur at the Stadttheater in Lübeck.

Joined the Berlin touring companies ‘Deutsche Musikbühne’ and ‘Deutsche Landesbühne’.

Conductor and pianist at the short wave broadcasting station Berlin, for which he composed numerous works and arrangements of folk songs from around the world.

Because of the German occupation of Holland, Koetsier was unable to return to his homeland as he had planned. Instead, he accompanied the dancer Ilse Meudtner as pianist on tours throughout Germany.

Conductor of the newly-founded Kammeropera in The Hague; tours throughout Holland.

Second conductor of the ‘Concertgebouw Orchestra’ in Amsterdam. Collaboration with Willem Mengelberg, then chief conductor of the orchestra, together with numerous guest conducting engagements.

Conductor of the ‘Residentie Orkest’ and conducting teacher at the Royal Conservatory in The Hague.

Principal conductor of the ‘Symphonieorchester des Bayerischen Rundfunks’, Munich (chief conductor, Eugen Jochum). Numerous studio productions with the performing groups of Bavarian Radio.

Professor of conducting and conductor of the orchestra at the Hochschule für Musik und Theater, Munich.

After retiring, Koetsier concentrated mainly on composing at his home in Rattenkirchen, Upper Bavaria. Numerous commissioned works for brass chamber groups resulted from his collaboration with ensembles, for example with the ‘Philip Jones Brass Ensemble’, the ‘Slokar Quartet’, the ‘Rennquintett’, the trombonist Armin Rosin and his ‘Brass Philharmonie’, the ‘Leipziger Hornquartett’, the ‘Münchner Blechbläsersolisten’ and other ensembles. His compositions also include many orchestral works, chamber music for various combinations of instruments, piano and organ music, songs, choral works and an opera (‘Frans Hals’, Op. 39).

Jan Koetsier was awarded the Order of Merit of the Federal Republic of Germany.

Jan Koetsier died on 28 April in the Augustinum Home in Munich.