The influence of foreign metal deposits (both upd- and opd-deposits) on a gold electrode on the rate of the redox reaction iron(II)/(111) oxalate has been studied with AC impedance measurements. An attempt has been made to rationalise observed changes in the rate of reaction in terms of changed metal-redox reactant interactions. Results obtained so far do not indicate significant changes in the adsorptive interaction as evidenced with Surface Enhanced Raman Spectroscopy despite the fact, that metal-adsorbate bands are pronounced. No correlations between band positions and their changes and changes of the catalytic activity could be observed.