A process for the removal of corrosion metal contaminants from a carbonylation catalyst solution comprising an iridium and/or rhodium carbonylation catalyst, an alkali and/or alkaline earth metal and corrosion metal contaminants in which the catalyst solution is contacted with a cation exchange resin having its active sites partially loaded with a sufficient amount of alkali and/or alkaline earth metal to maintain the concentration of said alkali and/or alkaline earth metal in the catalyst solution and recovering a catalyst solution of reduced corrosion metal contaminant content.