For efficient use of metal oxides, such as MnO 2 and RuO 2 , in pseudocapacitors and other electrochemical applications, the poor conductivity of the metal oxide is a major problem. To tackle the problem, we have designed a ternary nanocomposite film composed of metal oxide (MnO 2 ), carbon nanotube (CNT), and conducting polymer (CP). Each component in the MnO 2 /CNT/CP film provides unique and critical function to achieve optimized electrochemical properties. The electrochemical performance of the film is evaluated by cyclic voltammetry, and constant-current charge/discharge cycling techniques. Specific capacitance (SC) of the ternary composite electrode can reach 427 F/g. Even at high mass loading and high concentration of MnO 2 (60%), the film still showed SC value as high as 200 F/g. The electrode also exhibited excellent charge/discharge rate and good cycling stability, retaining over 99% of its initial charge after 1000 cycles. The results demonstrated that MnO 2 is effectively utilized with assistance of other components (fFWNTs and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) in the electrode. Such ternary composite is very promising for the next generation high performance electrochemical supercapacitors. KEYWORDS MnO 2; fFWNTs, PEDOT-PSS, supercapacitor, effective utilization.A s the limited availability of fossil fuel and the environmental impacts of a society based on such energy sources becoming more obvious, the need for renewable energy sources has attracted attentions of the world. Systems for electrochemical energy storage and conversion include batteries, fuel cells, and supercapacitors. Among them, supercapacitors, also known as electrical double layer capacitor, ultracapacitor, or electrochemical capacitor (EC), have attracted much attention because of their high power density, long cycle life (>100 000 cycles), and rapid charging-discharging rates.1 They can be applied in a large variety of applications, including consumer electronics, memory back-up systems, industrial power, energy management, public transportation, and military devices. More importantly, supercapacitors are critical components in the next generation all-electric cars and cars based on fuel cells that use hydrogen or alcohol as clean and renewable energy media.Various materials have been investigated as the electrodes in ECs, including carboneous materials, 2-4 conducting polymers 5,6 and transition-metal oxides. 7,8 MnO 2 is generally considered to be the most promising transition metal oxides for the next generation of supercapacitors because of its high-energy density, low cost, environmental friendliness, and natural abundance. 9,10The published results thus far established that the electrochemical performance of MnO 2 depended on their morphology, porosity, specific surface area, electrical conductivity and ionic transport within the pores. 11,12 In this context, layered mesoporous birnessite-type manganese oxide materials are attracting great interest due to their high surface area, low density, a...