In the present work, water-soluble electroactive methyl green (MG) has been used to non-covalently functionalize reduced graphene oxide (RGO) for enhancing supercapacitive performance. The microstructure, composition and morphology of MG-RGO composites are systematically characterized by UV-vis absorption, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrochemical performances are investigated by cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS). The fast redox reactions from MG could generate additional pseudocapacitance, which endows RGO higher capacitances. As a result, the MG-RGO composite (with the 5:4 mass ratio of MG:RGO) achieve a maximum value of 341 F g(-1) at 1 A g(-1) within the potential range from -0.25 to 0.75 V and provide a 180% enhancement in specific capacitance in comparison with pure RGO. Furthermore, excellent rate capability (72% capacitance retention from 1 A g(-1) to 20 A g(-1)) and long life cycle (12% capacitance decay after 5000 cycles) are achieved for the MG-RGO composite electrode. (C) 2015 Elsevier Ltd. All rights reserved.