Shell-core PtxRuy@PdCu catalysts comprising an outer PtRu shell, and inner PdCu core on a carbon support were prepared by a two-step process with controlled amounts of Pt and Ru to determine the effect of Pt/Ru ratio on methanol oxidation. The catalysts were characterized by TEM, XRD, XPS and electrochemical techniques. TEM of particle size distribution and average particle size found that neither changed significantly over the range of prepared Pt/Ru ratios. XRD and XPS analyzes found that the lattice parameter of Pt decreased with the increase of Pt/Ru ratio, which results in the downshift of the Pt d-band. The electrochemical active surface area reached a peak value at a Pt/Ru ratio of 2:1, indicating optimal Pt dispersion for methanol oxidation. In conclusion, optimization of the PtRu shell's component ratio significantly increases methanol oxidation and the efficiency of Pt usage. (C) 2013 The Electrochemical Society. [DOI: 10.1149/2.060304jes] All rights reserved.