NiPS, exhibits a high catalytic activity in thiophene hydrodesulfurization, as well as a hydrogenation and isomerization activity. The promoting effect of phosphorus on nickel-molybdenum hydrodesulfurization catalysts can be explained by the formation of highly dispersed NiPS3 under the reaction conditions. The mechanism of thiophene hydrodesulfurization over NiPS3 is discussed in relation to the pronounced ability of that substance to form intercalation compounds. A key step of the mechanism is the activation of hydrogen by intercalation in the van der Waals gap.