AbstractConsiderable amounts of ethanal may form in ethanol deep oxidation over platinum. The selectivity toward CO₂ increases at higher temperatures and at very low concentrations. An inhibiting effect of primarily formed aldehyde on ethanol conversion rate was observed; a power-law type equation rate is not applicable to describe the kinetics. The dependence of the selectivity on the contact time indicates that the gas-phase aldehyde may adsorb on the catalyst and further react to CO₂. At lower temperature direct complete oxidation to CO₂ and partial oxidation occur as parallel competitive reactions; at higher temperature a series-parallel mechanism takes place