Nanostructured, ternary SnO2-IrO2-Ta2O5 composites have been studied as promising electrocatalytic materials for oxygen evolution reaction (OER) in acid water electrolysers. Both unsupported and Ti-supported powders of the general composition Sn1-x-yIrx-TayO2+2 5y (x = 0, 0.03, 0.07, 0.15 and y = 0, 0.07) have been prepared by the same sol-gel route, and characterized in terms of structural (XRD) and morphological (SEM, BET) features, surface composition (XPS), and electrochemical behaviour (cyclic voltammetry, CV, electrochemical impedance spectroscopy, EIS, and slow potentiodynamic techniques). The results point out a dramatic variation of crystallite size and surface area with Ir and Ta doping of the SnO2 base matrix, accompanied by an improvement of the electronic and electrocatalytic properties of the composites. (c) 2006 Elsevier B.V. All rights reserved.