Micron size barium hexaferrite (BaFe12O19) platelets were prepared by the molten-salt synthesis method in various weight proportions of NaCl-KCl salt mixtures as a liquid medium. The effect of molten salt composition-x wt% NaCl and (100-x) wt% KCl-on the amount of barium hexaferrite phase formation, as well as, on the morphology and magnetic properties of the final products are discussed. Inductively coupled plasma-mass spectroscopy (ICP-MS) was used to determine the solubility of the starting materials in the salts in order to understand the formation mechanism of barium hexaferrite. X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) were used to identify the characteristics of the synthesized barium hexaferrite platelets. ICP-MS analysis showed that the Fe2O3 solubility is negligible, however, BaCO3 has very high solubility in both molten KCl and NaCl. Quantitative XRD and SEM results showed that molten salt containing 100 wt% NaCl at 900 degrees C (for 2 h) resulted in the highest production of barium hexaferrite. Further, SEM results showed that KCl-rich molten salt led to the formation of sharper faceted platelet morphology, whereas NaCl-rich ones resulted in more round platelets.