Electrochemical property of activated carbon monolith from potato powder was studied for possible application in supercapactor electrode. First, potato powder from local market was used to prepare column shape samples. Then, they were subjected to two-step pyrolysis to avoid cracking, such as the 1^st step at 300 °C at 0.5 °C/min heating rate and the 2^nd pyrolysis at 400, 500 or 600 °C under N₂ flow in a tube furnace. Next, the samples were cut into 2 mm thickness and immersed in 6M KOH solution, followed by the activation at 700 °C under N₂ flow. The residual K was dissolved out via dipping in 1M HCl solution. Finally, the electrochemical properties were evaluated with a three-electrode system by cyclic voltammetry, galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). In addition, two-electrode system was also studied with the samples having high specific capacitances. The samples were characterized by TGA and SEM, and specific surface area was also measured.