N-doped carbon materials offer a possible alternative to Pt-based oxygen reduction reaction (ORR) catalysts due to their high ORR performance and low cost. We present a facile, environment-friendly, approach to prepare Fe(III)-treated N-doped carbon materials from silk fibroin, a natural biomass source. Fe(III) treatment increased the total content of N and pyridine-like N on the carbon surface, resulting in significantly improved ORR performance. In 0.5 M H2SO4 solution, the catalyst has an ORR onset potential and the half-wave potential of 795 mV and 454 mV respectively, being only 86 mV and 134 mV less than those of commercial Pt/C (20 wt%) catalyst, and in 0.1 mol L-1 KOH solution are comparable to commercial Pt/C at 33 mV and -120 mV respectively. (C) 2014 The Electrochemical Society. All rights reserved.