A polyaniline-based, electron-conducting, glucose-permeable, redox hydrogel was formed in one step at pH 7.2 by cross-linking polymer acid-templated polyaniline with a water-soluble diepoxide, poly(ethylene glycol diglycidyl ether). Coimmobilization of glucose oxidase in the hydrogel, by co-cross-linking in the same step, led to the electrical wiring of the enzyme and to the formation of a glucose electrooxidation catalyst, allowing the electrocatalytic oxidation of glucose at a steady-state current density of 225 mu A center dot cm(-2) at 0.3 V vs Ag/AgCl.