The development of highly efficient non-noble metal catalysts for oxygen reduction reaction (ORR) is still a challenge in energy conversion and storage devices. Here we report a low-temperature strategy to synthesize ultrafine Fe and Fe3C nanoparticles anchored on nitrogen-doped mesoporous carbon (NMC). Iron precursors are synthesized through -60 degrees C liquid precipitation, then ultrafine and uniformly dispersed Fe and Fe3C nanoparticles are obtained by thermal treatment of the iron precursors. The prepared catalyst efficiently catalyzes 4-electron reduction of oxygen with half-wave potential (E-1/2) of 0.88 V in 0.1 M KOH, superior to the 20 wt% commercial Pt/C catalyst (E-1/2 = 0.86 V). The Fe/Fe3C-NMC electrocatalysts display remarkable stability and promising methanol tolerance. These new findings indicate potential new opportunities for exploring high ORR performance non-noble catalysts in electrochemical storage energy devices. (C) 2019 Elsevier Ltd. All rights reserved.