Radiation induced grafting of acrylic acid (AA) onto 40 mu m polytetrafluoroethqlene (PTFE) films was carried out by the direct method of multiple (discrete) and single irradiation from Co-60 source at different doses up to 100 kGy and room temperature. Depending on the method, the grafting takes place either on the surface layer or within the polymer matrix. The graft copolymers synthesized (PTFE-g-PAA) were transformed into ionomers by treatment with KOH. Both forms were used as carriers for immobilization of enzymes. The copolymers in H- and K-forms were activated by the acylazide method and glucose oxidase (GOD) was immobilized on them. The most suitable proved to be the ionomers PTFE-g-COOK obtained by single irradiation, possessing activity of ca. 120 mU/cm(2). Enzyme biosensor was designed based on Clark-type electrode and the active membranes prepared, where the membrane plays both the roles of enzyme and oxygen membrane. It can be used for determination of glucose in solutions.