The potential to improve the CO tolerance of a high temperature proton exchange membrane fuel cell (HT-PEMFC) was investigated by introducing a platinum-ruthenium alloy as anode catalyst. The electrolyte was a H3 PO4 doped poly-2,5-benzimidazole polymer (ABPBI). The experiments were carried out at the temperatures between 403 and 443 K with a CO concentration in the H2 feed gas between 0 and 6.5 vol%. The alloy anode catalyst lowers significantly the negative influence of CO in the feed, exceeding the known temperature dependent CO poisoning mitigation in HT-PEMFCs. It was found that the voltage loss of a HT-PEMFC with PtRu anode catalyst was lower than that of a similar cell equipped with Pt anode. The dynamic cell voltage response to a current step was analyzed under CO influence, as well. The PtRu bimetallic anode electrode was found to lower the observed voltage overshoot behavior after a current step, if compared to conventional Pt anode.