FIELD: chemical industry. SUBSTANCE: alkyl iodide impurities are removed from liquid composition comprising carboxylic acids having 2 to 6 carbon atoms or anhydrides thereof through layer of silver, mercury, palladium and/or rhodium substituted cation exchange resin of strong acid. Prior to reaction with metal substituted resin, the composition is reacted with cation exchanger in acid form to remove at least some metal ion impurities which appear due to corrosion of equipment and capable of forcing silver, mercury, palladium and/or rhodium out metal-substituted resin. EFFECT: more efficient impurity removal method. 7 cl, 3 tbl
