The presence in catholyte of trace metal ions has been reported to improve the current density and selectivity for several cathodic reductions of industrial importance. This paper reports a voltammetric investigation of the influence of Cu(II) in the catholyte on the reduction of trichloroacetic acid and of Pb(II) on the reduction of two substituted benzaldehydes. It is shown that the metal ions, even when present in concentrations of approximate to 1 mM, produce significant improvements to the voltammetry of the organic compounds. It is concluded that the improved electrochemistry results from the continuous, slow deposition of the metals onto the cathode surface leading to a "clean" surface with significantly different properties from electrodes fabricated from the same metal.