The proposed innovation utilizes carbon nanotubes (CNTs) coated with pseudo-capacitive MnO2 material as nano-composite electrode and ionic electrolyte for the construction of ultracapacitors. This novel approach of using nano-structured CNTs architectures provides high surface area of attachment of MnO2 nano-particles to maximize the charge efficiency and power capacity and to reduce series resistance. Preliminary results at Vanderbilt University using this CNTs/ MnO2 nano-composite as electrode of an ultracapacitor has demonstrated enhanced capacitor behavior of >400X over pristine CNTs as electrode. During Phase I, we will demonstrate in the laboratory that the proposed novel concept is feasible and measure the power and energy generation capacity, efficiency, and charging/discharging cycle durability. The key factor to successful exploitation of the CNT/ MnO2 nano-structured composite for ultracapacitor applications is closely related to further understanding and control of the physics, materials, and micro-fabrication technology. The proposed Phase I work provides a systematic, logical, and coherent investigation of the material issue, device fabrication, characterization, simulation, evaluation, and optimization to meet high power requirements.