A Pt-Ru-ads surface with 10% Ru adatoms was prepared by hydrogenating Ru(COD)(eta(3)-C3H5)(2) (1, COD is 1,5-cyclooctadiene) over Pt. The onsets of stabilized potentiodynamic oxidation for several fuels ([fuel] = [H2SO4] = 0.5 M, sweep range 0.025 to 0.60 V (vs. SHE), 5 mV s(-1), 22 degrees C)were ethanol (similar to 0.2 V), methanol (similar to 0.3 V), and 1,2-ethanediol (similar to 0.45 V). The activity of D-glucose was low under these conditions. The ratio of specific current densities for potentiostatic oxidation (30 min, [fuel] = [H2SO4] = 0.5 M, E = 0.4 V, 22 degrees C) over Pt-Ru-ads ana over Pt were methanol (42) 1,2-ethanediol (4.0), ethanol(2.3), and D-glucose (1.8).