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The oxidation of hydrogen containing carbon monoxide was studied on Pt-Fe electrocatalysts supported on a high surface area carbon powder. A good electrocatalytic activity was observed for anodes formed by this catalyst and supplied with H2 containing 100 ppm of CO, which presented overpotential loss of 250 mV at 1 A cm-2, compared to pure hydrogen. The on line differential electrochemical mass spectrometry has shown that the production of CO2 started at low potentials for PtFe/C, confirming that the CO tolerance is at least partially achieved by the bifunctional mechanism. However, X-ray absorption experiments showed an enhancement of the Pt 23/2-5d white line, compared to the Pt/C, indicating that the Pt atoms present more vacant 5d electronic states in the PtFe/C catalyst. This may lead to a change of the Pt-CO bond energy in this catalyst as compared to Pt/C.