A PtRuIr/C catalyst was prepared using a microwave-irradiated polyol plus annealing (MIPA) synthesis strategy and characterized by a series of techniques. The results are discussed in comparison with those for PtRu/C catalyst prepared in the same way;, they show insignificant difference in particle morphology, particle size, size distribution, phase structure, and compositional homogeneity. CO stripping voltammetry and single-proton exchange membrane fuel cell tests reveal that including Ir in the PtRu system results in an excellent COads electro-oxidation activity. Based on exploration of the structure-performance relationship, a speculative mechanism for the superior performance of the PtRuIr/C catalyst is proposed that suggests that the enhanced performance is attributed mainly to the interaction between RuO2 and IrO2, leading to facile oxidation of COads on active metal sites at a lower potential relative to the PtRu/C analogue. (c) 2006 Elsevier Inc. All rights reserved.