Evaluation of Co-Mo catalysts prepared onvarious TiO2-Al2O3 supports has been made for thiophene under atmospheric pressure, dibenzothiophene under high pressure and gasoil in a classical pilot plant. Comparison of activities indicates DBT as more representative of a real feedstock and the Co-Mo/TiO2 (50%)-Al2O3 (50%) catalyst appears more active than the Co-Mo/Al2O3 sample toward HDS, HDN and hydrodearomatization.