Semiconductor-based hetero-structure with desired compositions and/or morphologies can modulate the properties of materials and satisfy their potential applications. However, there is still a paucity of reports on the construction of the hetero-nanorod of metal oxides with multiple valencies in one material. In this work, the Mn3O4-MnO2 hetero-nanorods/graphene nanocomposite (MM-HNRS/GS) is successfully fabricated by combining a hydrothermal method (for MnOx nanorods), a wet chemical process (for composites) and a thermal treatment (for hetero-structures), and X-ray diffraction is adopted to demonstrate the formation process. Electrochemical results reveal that the hetero-structure based on Mn3O4 and MnO2 brings about a remarkable synergistic effect and markedly enhanced electrocatalytic activity for the reduction of H2O2. Taking advantage of the electro-reduction of hetero-nanorods and the high conductivity and large surface area of GS, MM-HNRS/GS exhibits excellent sensor performance in non-enzymatic and noble metal-free detection of H2O2, including a fast amperometric response (within 3 s), high sensitivity (1443 mu A mM (1)cm (2)) and low detection limit (0.16 mu M) (S/N = 3). In addition, good selectivity, reproducibility and stability are achieved. Considering the high sensitivity as well as the facile and low-cost preparation process, we expect this nanocomposite a promising electrocatalyst for electrochemical sensors. (C) 2016 Elsevier Ltd. All rights reserved.