Molybdenum disulfide nanoparticles supported on titania were synthesized from aqueous solutions containing Ti and Mo precursor salts by an in situ redox reaction. The synthesis involves a redox process between Ti3+ and MoS42−, which proceeds readily under mild conditions in aqueous solution. Catalysts were made in a single step, yielding amorphous catalysts with high Mo content, or in two steps to obtain MoS2 supported on well-defined TiO2 with lower Mo content. Catalysts obtained by single-step reductive coprecipitation were highly active in the hydrodesulfurization of dibenzothiophene, exceeding the activity of an alumina-supported Co–Mo reference. In contrast to alumina-supported catalysts, the addition of Co as promoter did not enhance the catalytic activity of MoS2/TiO2 to the same extent (+30 %) as for alumina-supported Co–Mo catalysts. Instead, a change in selectivity towards hydrogenolysis products at the expense of hydrogenation products was observed. It is suggested that Ti may act as a promoter for MoS2 in hydrogenation reactions.