Phase equilibria for the K2O-AI(2)O(3)-H2O System were investigated at 40 degrees C. In the concentrated alkali region of the phase diagram, only the equilibrium solid-phase K(2)O(.)Al(2)O(3)(.)3H(2)O was found besides (KOHH2O)-H-.. This is different from the fact of the similar system Na2O-Al2O3-H2O. Two invariant points with their respective equilibrium solid pairs (Al(2)O(3)(.)3H(2)O versus K(2)O(.)Al(2)O(3)(.)3H(2)O and K(2)O(.)Al(2)O(3)(.)3H(2)O versus (KOHH2O)-H-.) were identified with their corresponding compositions. These findings can provide a significant database for the removal of alumina from the concentrated alkali solution that was produced in the cleaner manufacturing process for chromium compounds. (c) 2005 Elsevier B.V. All rights reserved.