The solubilities of the K2CrO4 + KCI + KOH + H2O system at 20 degrees C, 40 degrees C, 60 degrees C, and 80 degrees C were determined by an isothermal method, and the phase diagrams were constructed. Meanwhile, the concentration of K2CrO4 in an aqueous solution of KOH was compared with that in an aqueous solution of KOH saturated with KCI. Lastly, analyses and discussions were made on the crystalline areas in the phase diagrams.