Water solutions of glucose (1.66 mol liter(-1)) were oxidized with air at 313 K on palladium catalysts supported on active charcoal. High gluconate yields (99.3%) were obtained in the presence of bismuth-promoted catalysis. Bismuth was deposited via a surface redox reaction on Pd/C catalysts containing 1- to 2-nm Pd particles. A STEM-EDX study showed that bismuth atoms are selectively and homogeneously deposited on the palladium particles. The catalyst can be recycled without loss of activity and selectivity. Bismuth was not leached from the catalyst during reaction and recycling. Bismuth adatoms prevent oxygen poisoning of the palladium surface by acting as a co-catalyst in the oxidative dehydrogenation mechanism. It was determined by calorimetric measurements that oxygen should adsorb preferentially on bismuth rather than on palladium.