The present work concerns a depolarization type bioelectrochemical fuel-cell with a bioanode consisting of a Micrococcus cerificans/glucose resting-cell system. Its response is interpreted in terms of an oxygen supplying zone (electrode) and an oxygen-consuming zone (cellular mass) separated by the cell membrane areas. The influence of the substrate and microorganism concentrations in the kinetics of the overall process is evaluated, and the maximum efficiency for cell design is discussed.