Phosphate-loaded mesoporous SBA-15 and SBA-16 materials were used as supports of novel ternary Co-Mo-W hydrodesulfurization catalysts. The effects of support morphology (SBA-15 against SBA-16) and its modification with variable amounts of phosphorus were studied. The sulfided catalysts were tested in a reaction of hydrodesulfurization (HDS) of dibenzothiophene (DBT) at 350 degrees C and 3.1 MPa of total H-2 pressure. The calcined, fresh sulfided and spent catalysts were characterized by a variety of techniques (N-2 adsorption-desorption isotherms, XRD,TPPTPD-NH3, DRS UV-vis, micro-Raman spectroscopy, XPS, HRTEM and TPO/TGA). Regardless of the support, it was found that the presence of phosphorous inhibited the HDS activity, and the catalytic response of both SBA-15- and SBA-16-based systems did not depend on the support morphology. In terms of the reaction rate constants (k), both CoMoW/SBA-15 and CoMoW/SBA-16 catalysts were more active than a CoMo/Al2O3 commercial catalyst containing a small amount of phosphorous in its formulation. in general, the spent CoMoW/(x)P-SBA-16 catalysts showed a lower coke formation than their SBA-15-based counterparts because the phosphate incorporation to the SBA-16 material led to decrease in coke formation in the final catalysts, as opposite to the behavior of SBA-15-based counterparts. (C) 2009 Elsevier B.V. All rights reserved.