Glucose oxidase was immobilized onto poly(2-hydroxyethyl methacrylate) membranes by covalent bonding through epichlorohydrin. The highest immobilization efficiency was found to be 17.4%. The K m values were 5.9 and 8.8 mM for free and bound enzymes, respectively, and the V max values were 0.071 and 0.067 mM/min for free and bound enzymes. When the medium was saturated with oxygen K m was not altered significantly but V max was. The optimum pHs for the free and bound enzyme were determined to be 5 and 6, respectively, and the optimum temperature was 30°C for both forms. The inactivation constant for the bound enzyme was found to be 1.7 × 10 −4 min −1.