In this work, the solution combustion synthesis method was implemented as a facile and in-situ procedure to adjust the composition of CuO/Cu2O composite by controlling the amounts of citric acid as fuel. Furthermore, the role of the Cu2O phase on the electrochemical properties was evaluated by preparation the single-phase CuO powders through calcination the CuO/Cu2O composite powders. The structural and microstructural results have shown that the synergic effects of Cu2O and CuO increased the electrochemical performance, including specific capacitance of 842 Fg−1 at 1 Ag−1 and high rate capability of 88 % by increasing the current density to 5 Ag−1. Furthermore, the CuO/Cu2O//activated carbon capacitor exhibited high electrochemical performance, such as an energy density of 27 Wh kg−1 at a power density of 1500 W kg−1 and outstanding cycling stability with 82 % capacitive retention for 2000 charge/discharge cycles, indicating a great potential for the practical application of CuO/Cu2O composite powders.