alpha-Amylase was immobilized on six poly(vinylamines) and three poly(vinylformamides) hydrogels polymerized using various techniques and crosslinkers. The enzyme was covalently bound to the Supports using glutaraldehyde as a spacer. The immobilization procedure was optimized involving such factors as temperature, pH, time, sequence of reactions, and kind of carrier employed. Results of the immobilization were evaluated based on analyses of the enzyme activity and stability prior and after immobilization, as well as on the immobilization yield and stability. Highly active biocomposite preparations were designed which provided their multiple application for starch hydrolysis. The selection of a carrier was essential for the activity and stability of immobilized a-amylase. Poly(N-vinylformamide) crosslinked with divinyl-benzene in form of spherical beads obtained in a suspension polymerization appeared to be a superior carrier for alpha-amylase. (C) 2008 Elsevier B.V. All rights reserved.