Sodium ion battery is a promising electrical energy storage system for sustainable energy storage applications due to the abundance of sodium resources and their low cost. In this communication, the electrochemical properties of sodium ion storage in reduced graphene oxide (RGO) were studied in an electrolyte consisting of 1 M NaClO4 in propylene carbonate (PC). The experimental results show that the RGO anode allowed significant sodium ion insertion, leading to higher capacity at high current density compared to the previously reported results for carbon materials. This is due to the fact that RGO possesses higher electrical conductivity and is a more active host, with large interlayer distances and a disordered structure, enabling it to store a higher amount of Na ions. RGO anode exhibits high capacity combined with long-term cycling stability at high current densities, leading to reversible capacity as high as 174.3 mAh g-1 at 0.2 C (40 mA g-1), and even 93.3 mAh g-1 at 1 C (200 mA g-1) after 250 cycles. Furthermore, RGO could yield a high capacity of 141 mAh g-1 at 0.2 C (40 mA g-1) over 1000 cycles. © 2013 Elsevier Ltd. All rights reserved.