A bipolar trickle tower reactor (BTTR) (of 7.9 cm internal diameter and 75 cm length containing 57 layers, each layer having 30 carbon Raschig rings, each of 1.25 cm outside diameter) has been studied under a range of operational conditions. The batch recycle mode of operation has been used for the removal of Cu(II) ions (at an initial concentration of 50-200 ppm) from an acid sulfate solution (typically 3000 cm(3)) at 295 K. Non-ideal flow and Peclet number values have been considered to establish the degree of deviation from ideal reactor flow models. Operational variables included the potential difference per layer (1.0-3.0 V), volumetric flow rate (8.3-50 cm(3) s(-1)) and the effect of H2SO4 concentration (which increased conductivity and lowered pH) in the electrolyte. The reactor has been shown to be best suited to the treatment of a moderately high reactant concentration (eg 100-200 ppm) and low electrolyte conductivity. The final concentration can be as low as a few parts per million but the performance of the reactor (as judged by the current efficiency and the rate of concentration decay) markedly decreased as the dissolved metal ion concentration fell. (C) 2004 Society of Chemical Industry.