Potentiostatic deposition of cuprous oxide (Cu2O) nanowires in polycarbonate membrane by cathodic reduction of alkaline cupric lactate solution has been investigated. These nanowires, characterized by scanning electron microscopy, have uniform diameters of about 100 nm and lengths up to 16 mu m. The electrochemical quartz crystal microbalance (EQCM) is used for in situ phase analysis measurements of the thin films, and the phase composition is determined by X-ray diffraction analysis. The electrochemical parameter limits for the deposition of nanowires are reported. The nanowires have been confirmed as crystalline Cu2O by powder X-ray diffraction, electronic nanodiffraction and energy dispersive X-ray spectroscopy. (c) 2005 Elsevier B.V. All rights reserved.