Water-dispersible 8-hydroxy-1,3,6-pyrene trisulfonic acid trisodium salt (PyS)-functionalized graphene (PyS-graphene) sheets were prepared by a pi-pi interaction method, in which the aromatic organic molecules of PyS were reacted with graphene. The PyS-graphene sheets were used as Pt nanoparticle support to prepare a Pt/PyS-graphene catalyst for direct methanol fuel cells. The prepared materials were characterized by ultraviolet spectrometry (UV-vis), Fourier transform infrared spectrometry (FT-IR), atomic force microscopy (AFM), X-ray diffraction (XRD), Raman spectroscopy (SERS), and transmission electron microscopy (TEM). The electrocatalytic properties of the catalysts for methanol oxidation were evaluated by cyclic voltammetry (CV). The Pt/PyS-graphene catalysts were found to have higher electrocatalytic activity for methanol oxidation than Pt/graphene catalyst. This finding can be attributed to the introduction of negative sulfonic (SO3-) groups to the graphene sheet surface, which makes the graphene sheets dispersible in water. Consequently, the Pt nanoparticles were uniformly and securely deposited onto the graphene sheet surface. These results suggested that the sulfonic group-modified water-dispersible graphene sheets can be used to improve the electrocatalytic activity of catalysts for fuel cells. (C) 2013 Elsevier Ltd. All rights reserved.