This paper presents a novel synthetic approach to synthesizing metal phosphides. Both bulk and supported Ni2P, Cu3P, MoP, and InP were synthesized by thermal decomposition of their metal oxide and hypophosphite precursors. Mechanistic studies of Ni2P were carried out using a separated-bed tube reactor, and the result indicates that NiO is reduced by PH3 (produced from decomposition of NaH2PO2) at 300°C. Ni2P hollow spheres were successfully synthesized by this method, which indicates that it is possible to synthesize metal phosphides with special morphology by using metal oxides with special morphology as precursors.