The objectives of this work are to provide new arguments for elucidating the influence of P added to a classical MoS2-γAl2O3 catalyst. The sulfided catalyst, activated by H2 at different temperatures TR in order to create anionic vacancies around the Mo sites was then tested in hydrogenation and hydrodenitrogenation reactions. It appears that P present in the catalyst acts directly on the support but also participates in the architecture of the supported active phase.