5M formic acid was anodically oxidized on a Pt/WO3 electrode at 50 mF/cm(2) over a test period of 175 h at 0.34 V vs. NHE at 20 degrees C without any poisoning effects. On a platinized electrode, at a fixed current density of 43.8 mA/cm(2), the potential was 0.43 V. The potential of the platinized electrode started to oscillate after a test period of 30 h and eventually shifted to the oxygen evolution potential.