After studying Romance philology and oriental languages : Sanskrit at the University of Liège (1962-1967), Jean Kellens was awarded a grant from the Belgian National Fund for Scientific Research (1969-1974), which enabled him to study at the University of Erlangen, with a school that was revolutionizing knowledge of ancient Indo-Iranian literature, and which led to a doctoral thesis (Les noms-racines de l'Avesta, Wiesbaden : Reichert 1974). He then became the " scientific collaborator " of Helmut Humbach, himself an alumnus of the Erlangen School, at the University of Mainz (1974-1982). This period culminated in a dissertation for the agrégation de l'enseignement supérieur (Le verbe avestique, Wiesbaden : Reichert 1984). Returning to Liège in 1983, he became professor of" History and Indo-Iranian languages " until his tenure at the Collège de France.