Ni2P catalysts supported on mesoporous silica (MCM-41) were prepared by temperature programmed reduction through a novel method using nickel(II) dihydrogenphosphite, Ni(HPO3H)2, as a precursor salt, and preparing three catalysts with nickel loadings of 5, 10 and 15 wt% denoted as Ni2P-x, where x is the percentage in weight of nickel. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and N2 adsorption–desorption isotherms were used to study the formation of the phase. The dibenzothiophene (DBT) hydrodesulfurization (HDS) activity was measured for Ni2P-x catalysts and they showed good TOF values at 400 °C. The conversion hardly changes with the metallic loading, and increases with temperature in all cases. On the other hand, Ni2P-5 catalyst shows a better intrinsic activity of Ni2P phase. Further, an improvement in the activity is found with time on stream, where an increase in both stability and activity are observed, reaching conversions of close to 95%. XRD and XPS analysis of spent catalysts show that the formation of a more active Ni2P phase takes place under the reaction conditions. The support impregnated with nickel(II) dihydrogenphosphite, without prior reduction, was also active in this reaction, increasing in activity with time on stream as a consequence of the formation of the corresponding Ni2P or other mixed NiPxSy phases under the experimental conditions.