The article demonstrates the influence of annealing temperature on the supercapacitance behavior of iron oxide nanotube synthesized on pure iron substrate by electrochemical anodization process. Anodization was performed in an ethylene glycol solution containing 3% H2O and 0.5 wt. % NH4F. The as-anodized nanotubes were annealed in an ambient atmosphere at various temperatures ranging from 200 to 700 degrees C for a fixed duration of time (2 h). The morphology and crystal phases developed after anodization and subsequent annealing processes were examined using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and X-ray photospectroscopy (XPS). Cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) experiments were performed in 1 M Li2SO4 to evaluate the electrochemical capacitance properties of the oxide nanotube electrodes. It was found that the electrode annealed at 300 degrees C exhibited superior electrochemical capacitance compared to the electrodes annealed at other temperatures. The highest specific capacitance achieved after annealing at 300 C was about 314 mF cm(-2). The electrodes annealed at 200, 500, 600 and 700 degrees C displayed much lower specific capacitance compared to those annealed at 300 and 400 C. Galvanostatic charge-discharge experiments conducted on some of the annealed electrodes demonstrated excellent cycle stability with more than 80% capacitance retention after 1000 charge -discharge cycles. (C) 2014 Elsevier B.V. All rights reserved.