The structural stability and transformations of Mo carbide, nitride and phosphide were investigated under various atmosphere conditions by X-ray diffraction (XRD). The results indicated that the order of structural stability of these Mo-based compounds was as follows: MO(2)N < MO(2)C < MoP. Both MO(2)C and MO(2)N can be transformed to MoP, whereas the reverse transformations did not occur. Noticeably, compared with those Mo sources containing oxygen, the use of MO(2)C/MO(2)N as Mo-source can produce finely dispersed MoP nanoparticles by the temperature-programmed reaction (TPR) method. The result was probably due to the fact that lower-levels H(2)O generated during synthesis process can avoid strong hydrothermal sintering. The influence of formation energy had been considered and was found to relate to the structural stability and transformations of these Mo-based compounds.