Rhenium sulfide based catalysts were prepared by the incipient wetness impregnation method over alumina and silica supports and evaluated for 4,6-dimethyldibenzothiophene hydrodesulfurization in a high-pressure stirred-tank reactor. The catalyst prepared over silica was about six times more active for hydrodesulfurization than the corresponding catalyst prepared over alumina and a NiMo/Al2O3 industrial reference catalyst. This surprising and positive SiO2 support effect was explained by a metallic character of the supported sulfide, which was demonstrated using a kinetic approach of competitive hydrogenations and by XPS characterization.