This study demonstrates that platinum-ruthenium (PtRu) nanoclusters decorated on a composite consisting of graphene sheets (GS) and carbon nanotubes (CNTs), denoted as PtRu/GS-CNT, show highly electrocatalytic activity for methanol oxidation with excellent carbon monoxide (CO) tolerance. Herein, restacking of individual GS is effectively inhibited by introducing one-dimensional CNTs to form a 3-D porous microstructure. From the SEM image, CNTs act as useful nanospacers for diminishing the face-to-face aggregation of GS. This 3-D porous structure exposes extensive surface area for evenly depositing PtRu nanoclusters and facilitates the electrolyte/reactant diffusion, leading to the highly catalytic performances of resultant materials. The voltammetric forward peak current density to the reverse peak current density for PtRu/GS-CNT(I-f/I-b = 6.33) is much higher than that of commercial catalyst, PtRu/Vulcan XC-72 (I-f/I-b = 1.33), revealing the synergistic effects between GS and CNT on enhancing electrochemical activities of PtRu nanoclusters for the methanol oxidation and the carbon monoxide (CO) tolerance. Therefore, the 3-D GS-CNT nanocomposite is a promising support material for dispersing noble metal catalysts in the fuel cell applications. (C) 2012 Elsevier Ltd. All rights reserved.