Plasma-induced graft copolymerization of acrylic acid, which was incorporated onto polyethylene (PE) film, was prepared. A bisamino poly(ethylene oxide) (PEO) was immobilized onto the poly(acrylic acid) (PAAc)-grafted PE membrane to modify the surface properties. The samples were characterized by ESCA. A respective chemical shift of Ar plasma-treated and control polymeric film was revealed by ESCA. The presence of the grafted PAAc and PEO was also verified. Glucose oxidase (GOD) was immobilized onto this novel grafted polymeric film with and without PEO being used as a spacer. The Michaelis constant, Km, and the maximum reaction velocity, Vmax, were estimated for the free and the immobilized GOD. GOD immobilized onto the polymeric films with and without a spacer obeyed Michaelis kinetics. The Michaelis constant, Km, was larger for the immobilized GOD than for the free one whereas Vmax was smaller for the immobilized GOD. The bioactivity of PEO-modified PAAc-grafted PE membrane (PAAc–PEO–GOD) was higher than that of PAAc-grafted PE membrane (PAAc–GOD). The pH and thermal stabilities of the immobilized GOD without a spacer (PAAc–GOD) were higher than those of the immobilized GOD with a spacer (PAAc–PEO–GOD) and the free form. © 1993 John Wiley & Sons, Inc.