AbstractPreliminary results on Pt‐based electrocatalysts prepared with CMK3 mesoporous carbons are presented. The electro‐catalytic performance towards the oxygen reduction reaction (ORR) was compared to that of commercial Pt/C‐Vulcan catalysts with the same Pt content. Polarisation tests were carried out with a single PEM fuel cell containing the Pt/OMC cathodes. The analysis of these tests, based on a semi‐empirical determination of the various polarisation terms, showed an interesting catalytic activity for ORR for the cathodes prepared with mesoporous carbon supports. The preliminary results indicate some critical aspects which need further investigation to improve the ohmic resistance limitation of these materials. Particularly, the variation of the grain size distribution with the Pt content and the effective distribution of Nafion® on the OMC surface should be considered.