High-performance hydrodesulfurization (HDS) catalysts were prepared by supporting Ni-Mo sulfides on a mixture of mesoporous MCM-41 and microporous HY zeolite. The mixed support was obtained either by physically mixing [MCM-41-HY(M)] or by overgrowing MCM-41 over HY zeolite particles [MCM-41 HY(C)]. Their HDS activities were tested in a trickle bed reactor at 280-340 degrees C, total pressure 5.0 MPa, H-2/feed ratio 1200 Nm(3) m(-3) and WHSV 27 h(-1), using a solution of 0.8 wt% DBT (dibenzothiophene) in decalin as the feed. A synergetic effect of the components in the mixed supports was observed on the supported Ni-Mo sulfides. NiMo/MCM-41-HY(M) exhibited both high HDS activity and hydrocracking activity, whereas NiMo/MCM-41-HY(C) showed a comparable HDS activity but a much lower hydrocracking activity. Moreover, the increase in HDS activity of either catalyst was accompanied by an enhancement in the hydrogenation pathway. The large difference between NiMo/MCM-41-HY(M) and NiMo/MCM-41-HY(C) in the hydrocracking activity may result from their different pore structures. (C) 2008 Elsevier B.V. All rights reserved.