The cathodic decomposition of InP at pH 9 was studied by cyclic voltammetry and X-ray photoelectron spectroscopy (XPS). Under cathodic conditions, the modified surface layer consists mainly of elemental indium (In). In the anodic range, In is converted into ln(OH)(3). The subsequent cathodic reduction of ln(OH)(3) to In does not take place to completion, and the amounts of In(OH)(3) and In increase irreversibly during cyclic potential scanning. (C) 2002 Elsevier Science B.V. All rights reserved.