In this work, two methods of preparing alumina-titania and ceria-titania mixed oxide supports were studied: In the first method, alumina or ceria were precipitated on the surface of a commercial titanium oxide. In the second method, alumina or ceria were impregnated on the surface of titania. In all catalysts under study, NiO comprises 3 wt% while MoO3 comprises 8 wt% in addition to 89 wt% of the support material. Surface area and pore volume measurements for the supports and catalysts were obtained from the analysis of nitrogen adsorption-desorption isotherms. Al, Ce, Ni, and Mo contents and coke percent of the spent catalysts were determined by x-ray fluorescence method. Characterization of the samples have been studied by DTA and XRD. The HDS activities have been studied, and two types of catalytic tests were used. One type of measurement was a screening test using the pulse technique. The second type was focused on studying the effect of important process variables as reaction temperature, hydrogen pressure, and LHSV on the extent of HDS of real gas oil (GO) feedstock and simultaneous HDS and HDN on the selected screened catalysts by using the continuous-flow high-pressure fixed-bed cata-test unit. The results revealed that titania containing Al or Ce catalysts are much more active than the conventional NiMo/Al2O3 catalysts on HDS and HDN reactions. They also demonstrate high aromatic saturation capabilities.