877-881Prolonged soaking of flame treated polycrystalline platinum surfaces in aqueous solutions of various inorganic acids for periods of hours to week resulted in formation of a new adsorbed H+(ads) / H (ads) couple as exhibited by a new redox peak in cyclic voltammetric study of the system. This adsorbed couple which has not been reported previously is accompanied by the adsorbed anionic species in two oxidation states. ln the case of sulphuric acid, the reduction of the oxidized form of adsorbed anion, namely persulphate, appears at ~ 450 mV/SCE while that of H+(ads) appears at 200mV/SCE at a potential sweep rate of 100mV/s. Both couples which are formed via the slow adsorption of species from aqueous solutions do not leave the surface upon cycling the potential between -400 to to 1400m V/ SCE and are clearly distinguished from their fast-equilibrating counterparts which exhibit peaks at different positions in the same voltammogram. Based on the amount adsorbed per unit area of platinum and the change of the size of the fast equilibrated hydrogen peak, it is tempting to assume H+(ads) residing beneath and H(ads) on the surface
