Three-dimensional freestanding hierarchical porous carbon materials with high specific surface areas (up to 1688 m(2) g(-1)) were prepared by the one-step carbonization of sucrose and zinc chloride (ZnCl2), defined as SCs for simplicity. Herein, ZnO particles served as the etchant and template to produce micropores and mesopores. The formation mechanism, morphology and structure were investigated by a series of techniques. The SCs exhibited highly enhanced electrochemical performances as supercapacitors, and the one synthesized at 800 degrees C (SC-800) showed high specific capacitances of 130 F g(-1) and 124 F g(-1) at the current densities of 1 and 20 A g(-1) in 1 M TEABF(4)/AN, respectively. This device delivered the high energy density of 55 Wh kg(-1) to afford the power density of 2.5 kW kg(-1) (voltage range of 3 V) and good cycling stability (85% capacitance retention after 10,000 cycles).