In this study, the immobilization of glucose oxidase (GOD) onto micron-size monodisperse Poly(Styrene-Glycidyl Methacrylate-Sodium Sulfonate Styrene) microspheres was investigated. In order to improve their surface biocompatibility, bovine serum albumin (BSA) was introduced onto the microspheres' surface as a new type of spacer arm. Both the immobilization amount and enzymatic activity were determined in different experimental conditions (enzyme concentration, pH, temperature, etc.). It was found that BSA could serve as a good spacer because it increases both the immobilization amount and enzymatic activity of GOD. The tolerance of immobilized GOD against pH, temperatures was examined. Moreover, the kinetic parameters for native and immobilized GOD were obtained and compared. (C) 2009 Elsevier B. V. All rights reserved.