Indium tin oxide (ITO) glass substrates are widely used in electrochemical devices and as substrates for in situ spectro-electrochemical experiments owing to their interesting optical, electrical and electrochemical properties. In this work, we found ITO surfaces to undergo substantial changes in their properties on potentiodynamic stresses in the acidic pH range. The surface changes occurring during cathodic cycling of ITO were characterized by redox couples in cyclic voltammetry, and the resultant surfaces examined by scanning electron microscopy (SEM), atomic force microscopy (AFM), optical transmittance measurements, X-ray diffraction (XRD) and the compositional changes by X-ray fluorescence spectroscopy (XRF). The studies of electrical, optical and structural properties of ITO during cathodic cycling in the acidic pH range clearly point to a set of conditions that help retaining the stability of ITO substrates intact for electrochemical applications. (C) 2007 Elsevier B.V. All rights reserved.