In this paper, the ion exchange isotherms of the two isoenzymes of glucoamylase from Aspergillus niger (named glucoamylase I and glucoamylase II) on the resin DEAE-Toyopearl 650 are presented and fitted to the Langmuir model and Henry＇s Law model, respectively. Furthermore, a comparative study between the adsorption behaviour of both isoenzymes has been performed which also includes the comparison between the monocomponent and bicomponent isotherms.