The effect of the support nature on the performance of Pd catalysts during partial oxidation of ethanol was studied. H 2 , CO 2 and acetaldehyde formation was favored on Pd/CeO 2 , whereas CO production was facilitated over Pd/Y 2 O 3 catalyst. According to the reaction mechanism, determined by DRIFTS analyses, some reaction pathways are favored depending on the support nature, which can explain the differences observed on products distribution. On Pd/Y 2 O 3 catalyst, the production of acetate species was promoted, which explain the higher CO formation, since acetate species can be decomposed to CH 4 and CO at high temperatures. On Pd/CeO 2 catalyst, the acetaldehyde preferentially desorbs and/or decomposes to H 2 , CH 4 and CO. The CO formed is further oxidized to CO 2 , which seems to be promoted on Pd/CeO 2 catalyst.