Enzyme entrapment in electrochemically polymerized membranes is an attractive method for the development of stable reproducible enzyme microsensors with fast response times. In this paper the development of a biosensor for the determination of glutamate, involving the entrapment of the enzyme glutamate oxidase in two different electropolymerization matrices, is described. Subsequently, the kinetics of the immobilized enzyme in the different matrices are compared, and the role of the polymers in providing a permselective barrier for the exclusion of potential electroactive interferents are characterized.