N-doped mildly oxidized CNTs (moCNTs) catalysts for oxygen reduction reaction in proton exchange membrane fuel cells were prepared by a two-step method consisting of polymerization and pyrolyzation. The morphology of the electrocatalyst samples were characterized by scanning electron microscopy (SEM), high resolution transmission electron microscopy (TEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). It was discovered that the N-doped moCNTs catalyst showed a graphene-like nanosheets nanostructure; electrocatalytic properties of the catalysts were investigated by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The experimental results exhibited remarkable catalytic activity in an acidic medium, with the onset potential, half-wave potential, and limiting current density reaching 0.87 V, 0.75 V (vs. reversible hydrogen electrode), and 3.5 mA/cm(2), respectively. It can be concluded that the high catalytic performance is due to the high content of graphitic nitrogen and the graphene-like nanosheets structure. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.