In this work, cobalt hydroxide nanoparticles are simply synthesized (size is about 50 nm) and deposited on the reduced graphene oxide nanoflake by the hydrothermal method. Then, the ability of glassy carbon electrode modified with this low-cost nanocomposite is examined as a supercapacitor and oxygen evolution electrocatalysts in 2.0 mol L-1 KOH by a three-electrode system. The modified electrode as a pseudocapacitor with potential windows of 0.35 V, exhibits a powerful specific capacitance (235.20 F g(-1) at 0.1 A g(-1) current density), energy density, stability (about 90% of the initial capacitance value maintain after 2000 cycles at 1.0 A g(-1)) and fast charge/discharge ability. Furthermore, the modified electrode displays a good electrocatalytic activity for oxygen evolution reaction with a current density of 10.0 mA cm(-2) at 1.647 V, small Tafel slope of 56.5 mV dec(-1), good onset potential of 1.521 V vs. RHE and suitable durability. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.