To realize a large-scale application of fuel cells, it is highly desirable to develop noble metal-free electrocatalysts for oxygen reduction reaction (ORR). Herein, a highly active electrocatalyst is synthesized by impregnating in situ generated iron(III)-1,10-phenanthroline complex on commercially high specific surface area carbon blacks and subsequent pyrolysis at high temperature. High ORR limiting current density (5.79 mA cm(-2)) and positive half-wave potential (0.859 V versus RHE) over this electrocatalyst with a mass loading of 0.2 mg cm(-2) can be achieved in 0.1 M KOH solution, which are very comparable with the benchmark Pt/C electrocatalyst. Detailed investigations have revealed the existence of nitrogen doped carbon (N-C), nitrogen coordinated to Fe (Fe-N), and Fe@Fe3O4 core-shell nanoparticles in this composite electrocatalyst. The high activity of this electrocatalyst is attributed to the synergistic effect among them. (C) 2015 Elsevier Ltd. All rights reserved.