The electro-oxidation of hydrazine on electrodispersed and electrofacetted Pt electrodes in acid solutions takes place without noticeable changes in the mechanism with respect to that followed on smooth polycrystalline Pt electrodes. Nonetheless, a negative shift in the oxidation peak potential is observed with increasing roughness factor, R, of the electrodes. By working with preferentially oriented electrodes it was possible to demonstrate that the shift towards more negative potential values of the hydrazine oxidation peak is due to a slightly higher proportion on the electrodispersed electrodes of(100) microfacets.