Alcohol oxidase was covalently immobilized onto magnetic beads of two different sizes, 75-150 mu m and 50-75 mu m in diameter, fabricated in the presence of glycidylmethacrylate and methylmethacrylate via suspension polymerization in the presence of a cross-linker (i.e., ethylenedimethylmethacrylate). The activity of the enzyme on smaller microspheres was found to be almost 4.8 fold higher than that of the larger counterparts. Although enzyme loading was same for both fractions, activity and the affinity of immobilized enzyme were significantly altered. The effects of various parameters such as temperature, pH, operational and storage stability were examined. The substantial change in the activity of enzyme was also observed in stability experiments in favor of large size magnetic beads. For all stability experiments including storage stability, the 75-150 mu m fraction was found to be more sentinel support for the enzyme. (C) 2007 Elsevier B.V. All rights reserved.