In this study, recently produced poly(hydroxypropyl methacrylate-co-methacrylic acid) gel beads were tried as a carrier matrix for the immobilization of ol-chymotrypsin (CT). A water soluble carbodiimide (WSC) activation procedure was applied for the covalent binding of CT via carboxyl groups of the selected carrier. The immobilization conditions (i.e., WSC and enzyme concentrations and immobilization pH) providing maximum retained activity after the immobilization were determined. The kinetic behaviour of immobilized a-chymotrypsin was investigated in a basket type batch reactor. The highest activity was observed at a pH of 7.8 for either free or immobilized enzyme. The temperature stability was significantly improved by the immobilization. The K-M value of immobilized CT was 140 mu M while the free enzyme K-M was 63 mu M No significant loss was observed in the activity of immobilized enzyme stored in an aqueous buffer solution at +4 degrees C for 8 months. (C) 2000 Elsevier Science B.V. All rights reserved.