LaCoO3 perovskite was successfully synthesized in molten NaCl-KCl eutectic mixture. Heating the La-nitrate, Co-nitrate and NaCl-KCl mixture to 800 degrees C yielded large (up to 5 microns) LaCoO3 cubic particles. Conversely, when La-and Co-nitrates were fed into the NaCl-KCl mixture, molten and stabilized at 800 degrees C, much smaller (sub-micron) particles were obtained. These results expound the mechanistic aspects of the perovskites formation in molten salts involving nucleation and crystal growth phenomena.