Nitrogen-doped carbon tubes (NCTs) with submicron diameters were synthesized by coaxial electrospinning and subsequent heat treatment in NH3 or N-2 atmosphere. Polyacrylonitrile (PAN) and polyvinylidenedifluoride (PDVF) mixture solutions were used as the outer fluids during coaxial electrospinning, and after heat treatment PAN converted into nitrogen-doped carbon species, while PVDF decomposed and left some pores in the tube walls. In comparison with the NCTs treated in N-2, the NH3-etched NCTs had a smaller diameter of about 350 nm and showed much better electrocatalytic activity for oxygen reduction reaction (ORR) in acid media. (C) 2013 Elsevier Ltd. All rights reserved.