Cathodic reductions involving solid metallic electrodes, like tin or lead, show the formation of unstable materials in which the presence of ammonium cations co-existing with negatively charged metal particles within the global structure has been fully demonstrated. Until now, similar behaviour of ammonium cations towards platinum cathodes has not been reported. This preliminary paper describes such cation behaviour in very dry solutions of dipolar aprotic solvent (e.g. dimethylformamide (DMF)) at freshly polished surfaces.