A series of MoP catalysts (MoP-CAx) were synthesized by adding citric acid (CA) to solutions of (NH4)6Mo7O24·4H2O and (NH4)2HPO4 with a fixed molar ratio of Mo:P:CA = 1:1: x (x = 0, 1, 4, 8) followed by drying and reduction in H2. The addition of CA had a significant effect on the microstructure (surface area and particle dispersion) and performance of MoP for dry reforming of methane (DRM). Among these MoP-CAx catalysts, the MoP-CA8 was found to show the highest catalyst stability, which should be attributed to the best matching of oxidation resistance ability and methane dissociation ability of MoP.