The two-dimensional sandwich-like Pt/Mn3O4/reduced-graphene-oxide (RGO) nanocomposites are successfully fabricated through a spontaneous and electroless approach, where Mn3O4 is rationally utilized as a green reducing agent in the synthesis of Pt nanoparticles and also a superior metal oxide support for the growth of Pt nanoparticles. By using X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy to characterize the catalysts, Pt nanoparticles are found to highly disperse on the Mn3O4/RGO surface. Electrochemical measurements indicate that the Pt/Mn3O4/RGO nanocomposites not only possess remarkably excellent long-time stability and electrocatalytic activity toward methanol oxidation, but also reduce the overpotential of methanol oxidation significantly, as compared to the Pt/RGO and the conventional Pt/C catalyst, which could be ascribed to the unique sandwich-like structure and the synergetic interaction formed between Pt, Mn3O4 and RGO. Therefore, the present approach provides some new clues for further development of two-dimensional sandwich-like electrocatalysts for fuel cells. (C) 2014 Elsevier Ltd. All rights reserved.