Phase equilibria of the system KOH-K2CrO4-K2CO3-Al2O3-H2O and its subsystems were investigated at 150 degrees C in the high alkali concentrated region. In the concentrated alkali region of the system and its subsystems KOH-K2CrO4-Al2O3-H2O and KOH-K2CO3-H2O, the equilibrium solid-phase K2CO3 center dot 1.5H(2)O was found. In the concentrated alkali region of the complex system, potassium aluminate and K2CO3 play an evident salting-out role to potassium chromate, respectively, and their combined operation lowers the solubility of K2CrO4. The solubilizing effect of K2CrO4 on Al2O3 in the system KOH-K2CrO4-Al2O3-H2O is similar to that of Na2CrO4 on Al2O3 in the system NaOH-Na2CrO4-Al2O3-H2O. These findings can provide a significant and precious database for the production of K2CrO4 and K2CO3 and the recovery of alumina from a concentrated alkali solution.