Benzene hydrogenation in steady-state and unsteady-state regimes over sulfide Ni-W/gamma-Al2O3 catalyst is studied. The mechanism and dynamic model of hydrogenation and hydrogenolysis active sites transformation are proposed. The reactions were shown to be quasi steady-state ones with slow poisoning of both hydrogenation and hydrogenolysis active sites by the formation of intermediate surface compounds of sulfur. The dynamic behavior was described by the proposed model with sufficient accuracy.