During his life three volumes of etudes written by Marinus Komst were published (“12 Etudes characteristiques”, “Dix études brillantes” and “15 études pour Trompette”). A fourth volume, the present “12 Exercises” composed by Marinus Komst in 1930, has never been published  before. A folder with manuscripts of these exercises (as Komst himself called them) was found by his biographer Ralph Henssen in a pile of sheet music from his estate. When Komst composed these virtuoso pieces he was only 22 years old. As far as we know he had no students yet, so it can be assumed that he composed these demanding exercises for himself.