A functional gas-diffusion electrode consisting of a modified platinum mesh electrode and a glass filter has been developed in order to convert CO2 to a useful substance at an overpotential as low as possible. The modification was made by laminating Prussian blue (inner) and polyaniline (outer) on a Pt mesh substrate. and a metal complex was further immobilized onto polyaniline. The improvement of the usefulness of the product and the required overpotential was brought about by using such functional gas-diffusion electrode in a KCl aqueous solution containing 10% propylene carbonate. This is attributed to the maintenance of a high concentration of CO2 at the electrode surface owing to the direct supply of CO2 through the gas phase. the high solubility of CO2 to the solution, and the stabilization of reaction intermediates. The maximum total current efficiency for the reduction of CO2 was 74.9% at -0.6 V vs. Ag/AgCl, and the main products were ethanol and lactic acid.