Graphene/alpha-MnO2 nanocomposite cathodes containing various amount of alpha-MnO2 catalysts (10 wt.%, 30 wt.%, 50 wt.%) were produced using planetary ball milling. The charge-discharge characteristics of the Li-O-2 cells with composite cathodes have been investigated from 2.15 V to 4.35 Vat a constant current density of 0.1 mA cm(-2) with ECC-Air cells. In order to investigate lithium oxide formation and decomposition reactions on the Graphene/alpha-MnO2 cathode, cyclic voltammetry test was performed at a scan rate of 0.1 mV/s. The Li-O-2 cell with a Graphene/alpha-MnO2 nanocomposite cathode containing 50 wt.% alpha-MnO2 exhibited a 6000 mAhg(-1) discharge capacity at full discharge, 2500 mAhg(-1) stable specific capacity up to 10th cycle at the state of 10 h charge and discharge and a 1250 mAhg(-1) specific capacity until 25th cycle at the state of 5 h charge and discharge. This study demonstrated that Graphene/alpha-MnO2 nanocomposite cathodes on nickel foam might be a good alternative cathode material for Li-O-2 batteries in the future. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.