To investigate the effect of thermal treatment of activated carbon on methanol adsorption, pulse-responses were measured in a gas chromatograph equipped with thermal conductivity detector (TCD), and reaction parameters were calculated by the moment method. Equilibrium adsorption constants and isosteric heat of adsorption of methanol decrease in the thermally treated activated carbon. This shows the decrease in the interaction between activated carbon and methanol due to the decrease of concentration of surface oxygen, which was confirmed by TPD experiment measuring the evolved concentration of CO/CO2 from the activated carbon. Regardless of thermal treatment of activated carbon, macro- and micro-diffusivities showed the value of same order of magnitude and surface and Knudsen diffusion prevails in micro and macro pore, respectively.