The research reports on the electrocatalytic properties of IrOx,Pt, and composite IrOx-Pt-IrOx, thin films prepared by physical vacuum deposition technique of dc magnetron sputtering. The efficiency toward the oxygen evolution in aqueous solutions and in a laboratory electrolyser with polymer proton conductive electrolyte has been investigated using the conventional electrochemical methods of cyclic voltammetry and steady state polarisation curves. The sputtered films have demonstrated excellent catalytic properties, mechanical stability, and high corrosion resistance under intensive oxygen evolution. The best performance (anodic current density of 0.84 A cm(-2) at potential of 1.8 V) has shown the IrOx film with loading of 0.2 mg cm(-2). Some data on the catalytic activity toward oxygen reduction reaction in aerated 0.5 M H2SO4 solution and the possibility to use the method of magnetron sputtering for preparation of cost effective composite catalytic films with bifunctional properties are also presented and discussed. (c) 2007 Elsevier Ltd. All rights reserved.