In the present work, with the aim of searching for new, highly effective catalysts for deep HDS, a series of NiMo catalysts with different MoO3 loadings (6-30 wt.%) was prepared using SBA-15 material covered with ZrO2-monolayer as a support. Prepared catalysts were characterized by N-2 physisorption, small- and wide-angle XRD, UV-vis diffuse reflectance spectroscopy, temperature-programmed reduction, SEM-EDX and HRTEM, and their catalytic activity was evaluated in the 4,6-dimethyldibenzothiophene hydrodesulfurization (HDS). It was observed that ZrO2 incorporation on the SBA-15 surface improves the dispersion of the Ni-promoted oxidic and sulfided Mo species, which were found to be highly dispersed, up to 18 Wt.% of MoO3 loading. Further increase in metal charge resulted in the formation of MoO3 crystalline phase and an increase in the stacking degree of the MoS2 particles. All NiMo catalysts supported on ZrO2-modified SBA-15 material showed high activity in HDS of 4,6-DMDBT. The best catalyst having 18 Wt-% MoO3 and 4.5 wt.% NiO was almost twice more active than the reference NiMo/gamma-Al2O3 catalyst. High activity of NiMo/Zr-SBA-15 catalysts and its evolution with metal loading was related to the morphological characteristics of the MoS2 active phase determined by HRTEM. (C) 2007 Elsevier B.V. All rights reserved.