NOVELTY - Preparation of nitrogen-doped carbon microspheres involves adding o-toluidine to aqueous solution of phosphoric acid, stirring, adding aqueous solution of hydrogen peroxide and aqueous solution of ferric chloride and stirring, transferring precursor solution to reaction vessel, placing in oven, heating, cooling to room temperature, centrifuging, removing upper layer supernatant, precipitating lower layer, washing with water and ethanol and drying, directly introducing poly-o-toluidine microspheres into vacuum tube furnace, heating under protection of nitrogen and cooling.    USE - The method is useful for preparing nitrogen-doped carbon microspheres, which are useful as an efficient oxygen reduction reaction electrocatalyst for fuel cell and an electrode material of supercapacitor.    ADVANTAGE - The method ensures preparation of nitrogen-doped carbon microspheres under mild reaction condition with less equipment consumption.    DETAILED DESCRIPTION - Preparation of nitrogen-doped carbon microspheres involves (a) weighing o-toluidine, hydrogen peroxide and ferric chloride in a molar ratio of 6:12-16:0.8-1, formulating hydrogen peroxide and ferric chloride into solution, adding o-toluidine to an aqueous solution of phosphoric acid, stirring, followed by adding an aqueous solution of hydrogen peroxide and aqueous solution of ferric chloride and stirring at room temperature for 10-15 minutes to obtain precursor solution, (b) transferring precursor solution to a reaction vessel, sealing reaction vessel and then placing in an oven, heating at 130-160 degrees C for 5-8 hours, cooling to room temperature, centrifuging, removing upper layer supernatant, precipitating lower layer, washing with distilled water and ethanol and drying in a vacuum oven at 40-80 degrees C for 6-12 hours to obtain poly-o-toluidine microspheres, and (c) directly introducing poly-o-toluidine microspheres into a vacuum tube furnace, heating under protection of nitrogen at 700-1000 degrees C and heating rate of 1-10 degrees C/minute, heat-preserving for 2-5 hours and naturally cooling.