An electrically insulated electrode was connected via a voltage source to the anode of a compact two-compartment microbial fuel cell, which employed yeast as the anode catalyst. Applying a dc voltage of 0.5 V between the anode and the insulated electrode caused the open-circuit voltage of the cell to increase from 0.3 V to 0.47 V. The dc voltage also extended the operation current and increased the power output of the fuel cell. Since no current was induced in the insulated electrode–anode circuit, no power was delivered by the voltage source to the fuel cell system. The electrostatic method appears as an additional parameter in the design of biofuel cells.