Reduction of (NH4)(2)MoS4 with N2H4 in aqueous solution in the presence of alumina suspension leads to the formation of a highly dispersed MoS2 supported on the surface of Al2O3. In the model thiophene desulfurization reaction, these MoS2/Al2O3 catalysts show a linear increase of catalytic activity as a function of Mo content up to 22 wt% of molybdenum. This preparation method makes it possible to efficiently disperse amounts of the active sulfide phase on alumina much higher than those of conventional systems prepared by impregnation. Promoted by Co, these materials exhibit a HDS catalytic activity much higher than that of a commercial CoMo/Al2O3 catalyst used as a reference.