In this project, an improved method for determining the electrochemical active area (ECA) of a platinum electrocatalyst has been developed. By the use of cyclic voltammetry, the ECA of a platinum electrocatalyst is measured by hydrogen adsorption. In the procedure, the charge used to form one monolayer of hydrogen is measured. The determination is influenced by the hydrogen evolution reaction and an accurate procedure is needed. Therefore, the hydrogen adsorption is modelled by three Frumkin-like adsorption isotherms. By performing a simulation of the measured cyclic voltammetry curves in the hydrogen adsorption potential region (hydride region), it has been possible to obtain a very accurate measure for the electrochemical active area. In this way, the current originating from the hydrogen evolution reaction can be sorted out. The procedure is used to characterise two different oxygen reduction electrodes both prepared from the same Pt/C catalyst with Nafion((R)) as binder.