The use of H-2 reduction instead of thermal decomposition of Pt-Ru/WO3/C catalyst precursor salts after freeze-drying resulted in significant improvement of the anodic oxidation of impure H-2. The electrode performance was 80 mA cm(-2) at 50 mV (80 degrees C, 0.5 M H2SO4) in H-2 containing 2% CO, and over 1600 mA cm(-2) in H-2 containing 100 ppm CO. Catalysts prepared by thermal decomposition of freeze-dried precursor salts had little activity for H-2 in a stream containing 2% CO. The use of CO stripping and electron microscopic examination showed that a higher surface area and greater number of Pt-Ru/WO3 interfaces are responsible for the improved performance.