The thiophene hydrodesulfurization activity was measured under continuous flow conditions at 400 °C and atmospheric pressure for Mo- and Co-containing catalysts supported on different materials (¿- and ¿-Al2O3 and SiO2) and using different methods of preparation. The results showed that all supports having a high specific surface area are suitable in HDS catalyst preparation. Alumina is to be preferred because it inhibits the formation of CoMoO4, and thus exerts a beneficial influence on catalyst preparation. The main function of the support is to stabilize a high degree of dispersion of the actual active component MoS2. In addition the carrier may facilitate hydrogenation and isomerization reactions.