RuO2 films containing Pt nanoparticles were prepared by a sol-gel route on Ti substrates, The effects of nominal composition of the film and of two different atmospheres used during the densification heat treatment on the electrochemical response were studied. Composition and structural and morphological characteristics were analyzed by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. The general aspects of the electrochemical behavior were studied by cyclic voltammetry in HClO4 acid aqueous solution. The oxygen evolution reaction (oer) was studied by means of very slow, potential sweeps and chronoamperometry. It was found that these materials exhibit a fairly good electrocatalytic activity towards the oer. Tafel coefficients of 60 and similar to 100 mV dec.(-1) were obtained, in the low, and high overpotential regions. respectively, (C) 2003 Elsevier Science B,V. All rights reserved.