Heteroatom-doped carbon materials and their composites with transition metal or transition metal oxides have attracted great attention as oxygen reduction reaction (ORR) electrocatalysts due to their low cost and good catalytic activity. Here the composites of Co/CoO and N-doped carbon sub-micrometer spheres (Co/CoO/NCS) derived from chitosan, EDTA and cobalt salts were prepared via a process of forming of chitosan spheres-absorption of Co2+-calcination and their ORR catalytic activities were investigated. Among the series of catalysts of Co/CoO/NCS, the sample (CS1:3-Co-900) with the weight ratio of chitosan/EDTA being 3:1 and calcinated at 900 degrees C displayed the optimum ORR catalytic activity comparable to that of commercial 20% Pt/C, good long-term stability and excellent methanol tolerance. In addition, the effect of the weight ratio of chitosan/EDTA and the calcination temperature on the ORR catalytic activity was also studied in detail. This study provides not only a new way to prepare highly efficient ORR electrocatalysts, but also sufficient data to uncover the mechanism of such catalysts. (C) 2017 The Electrochemical Society. All rights reserved.