Ni₂P catalysts supported on SiO₂ and SBA-15 were successfully prepared by temperature-programmed reduction (TPR), and the effect of Ni₂P dispersion on the 4,6-dimethyldibenzothiophene hydrodesulfurization (HDS) activity was studied. The surface areas of the samples varied from low (Ni₂P/SiO₂, 127 m² · g⁻¹) to high (Ni₂P/SBA-15, 283 m² · g⁻¹), with corresponding Ni₂P average crystallite sizes decreasing from 20 to 5 nm. Extended X-ray absorption fine structure (EXAFS) studies were used to confirm the formation of Ni₂P phase. Transmission electron microscopy (TEM) analysis showed that the SBA-15-supported Ni₂P sample consisted of nanoparticles, which were probably located in the mesoporous channels or the external surfaces. The catalytic activity for HDS was measured at 613 K and 3.1 MPa in a three-phase fixed bed reactor using a model liquid feed containing 500 ppm S as 4,6-dimethyldibenzothiophene, 1000 ppm S as dibenzothiophene, 200 ppm N as quinoline, and 1% aromatics as tetralin in tridecane solvent. The Ni₂P/SBA-15 catalyst had a steady-state HDS conversion of 99% at 613 K, much higher compared to the Ni₂P/SiO₂ catalyst with a HDS conversion of 54%. These results are probably due to the enhanced dispersion of the Ni₂P particles on the high surface area SBA-15 support, as confirmed by CO chemisorptions, TEM and EXAFS analysis.