The graphene/polyaniline (PANI) composite hydrogel was successfully prepared by a one-step hydrothermal method. The morphology and structure of the sample were characterized by digital camera, scanning electron microscopy, and Fourier transform infrared spectroscopy spectra. By combining the advantages of high conductivity of graphene and high pseudocapacitance of PANI, the composite hydrogel was taken as supercapacitor electrode material. Cyclic voltammetry and galvanostatic charge/discharge experimental results show that the composite has excellent electrochemical performance. The specific capacitance value is 258.5 F g(-1) at a scan rate of 2 mV s(-1) and the specific capacitance value is up to 307 F g(-1) at a current density of 0.2 A g(-1). The specific capacitance value can still maintain 90 % of the initial value after repeating the galvanostatic charge-discharge for 1000 cycles at a current density of 1.0 A g(-1) showing good cycle stability.