Activated carbon nanofibers with hollow core/highly mesoporous shell structure (Meso-HACNF) are prepared by concentric electrospinning using poly(methyl methacrylate) (PMMA) as a pyrolytic core precursor with either polyacrylonitrile (PAN) or PAN/PMMA blended polymer as a carbon shell precursor, subsequently proceeded to the process of stabilization, carbonization, and activation. Meso-HACNFs with two different PMMA concentrations, 10 wt.% and 20 wt.%, are composed of a highly mesoporous shell and hollow core while HACNF without PMMA is composed of a relatively small mesoporous shell and hollow core. Highly mesoporous Meso-HACNE1 has a large surface area of 1191 m(2) g(-1) with a mesoporous surface area of 151 m(2) g(-1). Meso-HACNE1 with 10 wt.% PMMA has a high efficiency of 7.21%, and is comparable to Pt CE because of its novel characteristics, which promote the electron and ion transfer, decrease the resistance of charge transfer, and increase the contact area between liquid electrolyte and Meso-HACNF1. (C) 2013 Elsevier B.V. All rights reserved.