The kinetics of hydrogenation of m-xylene and tetralin were determined on a commercial sulfided NiMo on gamma-Al2O3 catalyst at 7.0 MPa and over 280-310 degrees C. The experiments were done in a fixed-bed unit under pseudo-first-order kinetic conditions. It is shown that the activation energies for hydrogenation of tetralin and m-xylene are comparable, and the hydrogenation rate of tetralin is about twice that of m-xylene. This approximate 2-fold difference in reactivity is comparable to that observed with unsupported MoS2 reported previously under more severe conditions.