A ternary electrode material, based on graphene, tin oxide (SnO2) and poly(3,4-ethylene-dioxythiophene) (PEDOT) has been obtained via one–pot synthesis for supercapacitors. The resulting composite graphene/SnO2/PEDOT (GE/SnO2/PEDOT) shows excellent electrochemical stability in acidic electrolyte, and good electrochemical performance with enhanced capacitance and energy density in both acidic and neutral electrolytes, compared to their binary composites. A maximum specific capacitance of 184Fg−1 in 1M H2SO4 and 180Fg−1 in 1M Na2SO4 respectively was obtained. Its energy density reaches 22WhKg−1 at a power density of 238.3Wkg−1, and 17.1Whkg−1 at a high power density of 5803.3Wkg−1 in H2SO4. While in Na2SO4, the energy density achieves 23.4WhKg−1 at a power density of 253Wkg−1 and 10.2WhKg−1 at power density of 3684Wkg−1, respectively. The specific capacitance can still be retained about 100% and 70% at 1Ag−1 after 5000 cycles in 1M H2SO4 and Na2SO4, respectively. The improved electrochemical property of GE/SnO2/PEDOT as electrode materials is mainly ascribed to the well-designed ternary nanostructure of the functional components with enhanced synergistic effects.