A high surface area molybdenum phosphide (MoP) was successfully synthesized by combining citric acid (CA) and temperature-programmed reduction (TPR) (CA-TPR) method. Reduction of the precursor which was modified by citric acid produced Mol? with a high surface area of 122.0 m(2) g(-1) under optimum conditions. Fourier transform infrared (FTIR) results showed that the chelating interaction between the moderate amount of citric acid and the molybdenum ion was effective in suppressing the aggregation of Mo during drying through the formation of a molybdenum citrate, which was decomposed in calcination. Reduction of the precursor from the CA-TPR method showed an obvious decrease in degree of the aggregation of the MOP particles when compared to that from the conventional TPR method. The Mol? prepared by the CA-TPR method was characterized by X-ray diffraction (XRD), N-2 adsorption-desorption, TPR, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and CO adsorption microcalorimetry. An increase in reduction temperature led to the formation of MoP crystalline and a change of morphology. The increase of surface area in the reduction process was a result of the formation of pores. The porous MoP from the CA-TPR method had a higher CO chemisorption uptake than from the conventional TPR method, indicating that the high surface area MoP possessed more active sites. The preliminary testing showed that the high surface area MoP exhibited a superior activity for hydrazine decomposition with a conversion of 85%, which was much higher than the conventional Mol? of 55%. (c) 2006 Elsevier B.V. All rights reserved.