We have developed a mixed system, etectrochemical-microbiological, that can be used for detoxifying organic compounds present in wastewater. In this system, organic matter oxidation takes place at the anode of an electrochemical reactor while ferric iron reduction takes place at the cathode. We have used a growing culture of Thiobacillus ferrooxidans to regenerate the ferric ions consumed. The culture is used as the catholyte (solution in the cathode compartment) of the system and is therefore permanently subjected to an electric field. We have verified that, under our working conditions, the culture is able to oxidize ferrous ions for long periods of; time (up to 15 days) depending on the intensity of the applied current. We have checked the performance of this system in methanol oxidation. Our results show that it decreases the energy cost by 35% when compared with the pure electrochemical system traditionally used.