Adsorption of aniline on smooth polycrystalline platinum was studied in 0.5 M H2SO4 aqueous medium as a function of the aniline concentration (10(-8)-10(-3)M) and electrode potential (-670 to +1000 mV (MSE)) by potential programmed voltammetry. The adsorption kinetics and isotherms were investigated at constant potential. Possible orientation models were proposed for adsorbed compound.