By using voltammetric and subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTIRS) techniques it has been demonstrated that C1 and C2 compounds (methanol, formaldehyde, ethanol and acetaldehyde) are dissociatively and irreversibly adsorbed on polycrystalline platinum surfaces in a carbonate medium, forming linear and multibonded CO. In this medium, the shape of the band corresponding to linearly bonded CO is monopolar as a consequence of the partial overlapping of the absolute absorption bands at each potential.