We present the results of a numerical calculation of the space charge first described in a model proposed by Chazalviel to explain the onset of ramified growth in electrodeposition from a binary electrolyte. Our results confirm that, when the ionic concentration goes to zero at the cathode the system departs from electroneutrality. However, the excess of positive charges at the cathode critically depends oil the parameters of the system. In typical conditions, it may rise up to 10(-4) mol/L. The extension of the space charge region is approximately 200 nm. (c) 2005 Elsevier B.V. All rights reserved.