Electrical double layer capacitor (EDLC) is a major group of supercapacitors. The capacitance of EDLC comes from the pure electrostatic charge at the electrode interface. Therefore, the capacitance of EDLC depends on the surface area of the electrode materials accessible to the electrolyte ions. Porous (Activated) carbons are ideal materials to make electrodes not only because of its good electrical conductivity, high surface area, and chemical stability, but also because they can be derived from sustainable resources. Herein, this project first describes the general information of EDLCs including basic theory, history, components and materials. The second achievement of this project is to build “green” supercapacitors with porous carbon. In order to achieve the green approach of supercapacitors, the porous carbon is made from starch, a cheap and reproduceable carbonaceous material. By using hydrothermal carbonization (HTC) and KOH activation, the process of making porous carbon requires less carbon input and produces less toxic byproduct. The electrochemical properties of the electrodes made were characterized using cyclic voltammetry (CV). The various characterization schemes used revealed that the utilization of KOH during activation process yielded carbon sponge possessing large surface areas and with substantial capacitances over 150 F/g in 1.0 M Na2SO4 electrolyte. In all, this capstone not only achieves the intended goal of building a “green” supercapacitor with high capacitance, but also proposes a simplified path for activating carbon.