In this research, different nanostructures of cobalt phosphate were successfully prepared. Flowerlike cobalt phosphate and platelike ammonium cobalt phosphate were made by coprecipitation method without any use of surfactant or capping agent as structure directors. Reverse micelle route in water/CTAB/n-hexanol microemulsion system was used to synthesize cobalt phosphate nanoparticles. The synthesized nanostructures were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), chemical analysis, and BET. The SEM images showed that the flowerlike nanostructure is an arrangement of cobalt phosphate plates. TEM images revealed that the nanoparticles are spherical with the diameter of 30-50 nm. The purity of cobalt phosphate nanoparticles was confirmed by chemical analysis. Finally, the possible mechanisms which can describe the formation of these nanostructures were discussed. (C) 2010 Elsevier Ltd. All rights reserved.