Nickel phosphide catalysts supported on the TiO2-Al2O3 composite oxide were successfully prepared by impregnation of nickel phosphate precursors followed by temperature-programmed reduction. The catalysts were characterized by X-ray diffraction, thermogravimetric analysis, IR spectroscopy, N-2 adsorption, and X-ray photoelectron spectroscopy. The catalytic activity was characterized in a fixed-bed reactor for hydrodesulfurization using a model liquid-feed dibenzothiophene, which contained 2000 mg/kg sulfur. Experimental results indicate that the TiO2-Al2O3 composite support effectively prevents the formation of aluminum phosphates due to the strong interaction between phosphorus and gamma-Al2O3, and it also shows strong interactions with Ni and P species on the surface, which is the main reason for the enhancement in hydrodesulfurization activity and stability. Among the Ni2P/TiO2-Al2O3 samples tested, the catalyst at a Ni loading of 15 wt % showed the highest activity with a steady-state dibenzothiophene conversion of 99.9% at 613 K, 2.5 MPa, WHSV 3 h(-1), and volume ratio of hydrogen/oil of 450.