Abstract: In order to explore the effect of surface modification on pore structure and thermal-electric energy conversion of activated carbon, activated carbons were first modified by surface treatment using HNO₃ and KOH under different conditions. The pore structure and graphitic-type structure of the activated carbons were characterized by N₂ adsorption and XRD. The specific surface area and pore volume of the activated carbon are significantly increased by the surface treatments, while the average pore size and presence of graphite crystal structure are slightly affected. For the dry modification method, the specific surface area and pore volume are increased from 1 077.880 m²/g and 0.763 cm³/g to 1 635.268 m²/g and 1.128 cm³/g, respectively. Furthermore, after modification, the micropore volume is increased and the impurities of the activated carbon are removed. The performance of thermal-electric energy conversion of the activated carbon is tested by using the activated carbon as solid electrode materials and KCl solution as electrolyte, which shows the treated activated carbon has better performance.