Presulfided CoMoS/gamma-Al2O3 catalysts with sharp and deep eggshell concentration profiles of Co and Mo were prepared by a simple method and their properties were characterized by EDS, HRTEM, and FT-IR techniques. It was found that the Co eggshell thickness of the as-prepared catalysts could be conveniently regulated by controlled evaporation depth of the pre-soaked n-decane in the outer layer of the catalyst extrudates prior to the impregnation process, and the remaining n-decane in the core of the extrudates could prevent the diffusion of the acetone impregnation solution of Co(NO3)(2) into that zone of extrudates. The evaluation results of the catalytic performance in hydrodesulfurization (HDS) of dibenzothiophene (DBT) indicated that the eggshell catalysts showed higher HDS activity than that of the uniform catalyst. That was because the eggshell catalysts could remarkably decrease the internal diffusion limitation effect due to a short diffusion path of the reactant. In addition, the eggshell catalysts could greatly improve the utilization efficiency of the active components. (C) 2011 Elsevier Ltd. All rights reserved.