Glucose oxidase was immobilized by electropolymerization into films of polyaniline, polyindole, polypyrrole, poly(o-phenylediamine), and polyaniline crosslinked with pphenylenediamine. The kinetics and the behavior of the entrapped enzyme toward elevated temperature, organic solvent denaturation, and pH were investigated, along with the response of the films to electroactive species such as acetaminophen, ascorbate, cysteine, and uric acid. For most of the films, linearity to glucose extended from 7 to 10 mM. The poly(o-pheny1enediamine)lglucose oxidase film gave the best signahoise ratio and polypyrrole/glucose oxidase film gave the most reproducible current responses. No significant shift of the optimum reaction pH (5.51, except for polypyrrole (5.0), was observed after immobilization of glucose oxidase in the various films. Enzymatic activity decreased rapidly when pH was raised above 7.5. Thermodeactivation studies at 55", 60", and 65ยฐC have shown polypyrrole/and poly(o-phenylediamine)/glucose oxidase films to be the most resistant enzymatic films. Poly(o-phenylenediamine) films offered the best protection against glucose oxidase deactivation in hexane, chloroform, ether, THF, and acetonitrile when compared with the other electropolymerized films. All the enzymatic films exhibited permselection toward electroactive species.