A process is described for recycling catalysts in the reaction for the oxidation of alcohols and/or ketones to carboxylic acids and more particularly the oxidation of cyclic alcohols and/or cyclic ketones to dicarboxylic acids, such as the oxidation of cyclohexanol and/or cyclohexanone to adipic acid. This process involves treating the solution comprising the oxidation catalyst, before it is recycled, with an ion-exchange resin which makes it possible to selectively separate the iron from the other metal elements, in particular from copper and from vanadium.