An endo-pectinlyase present in a commercial mixture was immobilized on EUDRAGIT L100-55, a polymer which is reversibly soluble-insoluble depending on the pH of the medium. The enzymic activities of biocatalytic matrices, obtained by pre-activating the polymer either with water-soluble carbodiimide or by simple adsorption, were compared The biocatalyst obtained by adsorption showed an enzymic activity higher (500 E.U. g(-1)) than that obtained using the activated polymer (50 E.U. g(-1)). Moreover, the activating agent did not seem to be necessary in order to stabilize the interaction between carrier and protein. In fact about 80% of the initial activity was detectable on both matrices after repeated washings with NaCl 0.2 M, The immobilization procedure did not alter the main biochemical parameters of the immobilized enzyme with respect to its native form and appreciably enhanced its stability in the temperature range 25-45 degrees C.