Highly efficient and metal-free electrocatalysts hold promising in industrial water electrolysis with low cost, environmental friendliness and structural stability in wide pH electrolyte. Herein, N and O dual-doped carbon fiber (CF-O-N) has been hydrothermally synthesized as a three-dimensional (3D) electrocatalyst for oxygen evolution reaction (OER). The co-doping of N and O atoms acts as dual-active-site to improve OER properties, while the rough surface and large pores in CF-O-N electrode may expose abundant active sites and sufficient contacting in catalyst/electrolyte interfaces. CF-O-N electrode behaves excellently for OER with only 130 and 590 mV to generate 10 mA cm(-2) and 100 mA cm(-2), respectively. The superior OER property of CF-O-N electrode than single N- or O-doped CF implies the synergistic effect between N and O dopants that may further enhance OER activities. More importantly, dual-doped CF-O-N electrode displays roust stability in 10,000 cycles of cyclic voltammogram (CV) and 12 h chronoamperometry test with unchangeable structures proved by post physical characterizations. It may provide a facile and rational design of self-supported and metal-free materials with excellent activities for water oxidation and holds promising for further industrialization. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.