Electrodes based on carbon-supported platinum electrocatalysts (Pt/C) have been studied in aqueous electrolyte electrochemical cells. The electrodes are prepared from suspensions of commercial Pt/C catalyst, deposited onto a carbon-covered Pt disk. Three deposition methods have been used, impregnation, spray and electrospray. The utilisation of Pt, i.e. the amount of Pt that really participates in the electrochemical reaction, was determined for each preparation method from measurements of the mass of Pt deposited on the electrode, and of the electroactive area of Pt. Higher utilisation rates are found on electrodes prepared by the impregnation method. The activity towards oxygen reduction in aqueous electrolyte was studied with the rotating electrode at different temperatures. (c) 2005 Elsevier B.V. All rights reserved.