From galvanostatic potential-time curves, voltammograms and impedance measurements, it is shown that the destabilization of the zinc deposition process by Ni2+ ions present in the acidic sulphate electrolyte is considerably favoured in the absence of a diaphragm separating the anode and cathode compartments. It is concluded that the deleterious influence of Ni2+ ions is enhanced by the anodically formed products which interfere with the slow interfacial processes taking place at the cathode surface. A stronger synergetic influence of nickel and oxidized species is demonstrated when using an aluminium cathode containing Fe impurities.