The phase equilibria for the system KOH-K2CrO4-Al2O3-H2O and its subsystems at 150 degrees C in a high alkali concentrated region were investigated. In the concentrated alkali region of the system and its subsystem KOH-Al2O3-H2O, the equilibrium solid-phase K2O center dot Al2O3 center dot 2H(2)O was found. This is different from the system KOH-Al2O3-H2O at low temperature from which tie equilibrium solid-phase K2O center dot Al2O3 center dot 3H(2)O was discovered. The salting-out effect of KOH and potassium aluminate to K2CrO4 is strong. These findings can provide a significant and precious database for the production of K2CrO4 and the removal of alumina from the concentrated alkali solution that is produced in the chromate cleaner production process.