This work reports the influence of thermal treatment on electrocatalytic water oxidation/ reduction behaviors of one dimensional CoTe nanotube film deposited on FTO substrate from aqueous solution at room temperature. The optimally annealed film at 200 degrees C demonstrates substantially better electrocatalytic properties, which can be ascribed to the enhanced electrochemical active surface area and electrical conductivity obtained by improving the intergranular connectivity. In addition, the annealed nanotube film demonstrates highly competitive performance to that of many outstanding electrocatalysts for overall splitting of alkaline water to generate hydrogen as green fuel with the oxygen evolution reaction overpotential of 0.37 V (without iR- compensation) for the benchmark current density of 10 mA cm (-2). (c) 2017 Elsevier Ltd. All rights reserved.