Some basic work has been performed on the development and optimisation of superoxide dismutase (SOD) biosensors for superoxide radical analysis. Initially we studied the possibility of obtaining a SOD biosensor using the Clark electrode as indicating sensor. However, the best results were obtained using as indicator a classical amperometric electrode for H2O2. In both cases the superoxide radical was generatedin situusing the xanthine/xanthine oxidase (XOD) enzyme system, while the SOD was immobilised in kappa-carrageenan gel. The first application was realised by studying the effectsin vitroon the superoxide radical of some molecules commonly accepted as radical scavengers.