In this study, the correlation between n-butane adsorption characteristics and pore characteristics of activated carbons (ACs) was investigated by activated polymer-based hard carbons (APHCs) using a carbon dioxide activation method. The structural characteristics of the ACs were observed by X-ray diffraction and Raman spectroscopy. The N-2 adsorption isotherm characteristics at 77 K were confirmed by Brunauer-Emmett-Teller, Barrett-Joyner-Halenda, and nonlocal density functional theory equations. From the results, specific surface areas and total pore volume of the ACs were determined to be 1020-2440 m(2)/g and 0.42-1.30 cm(3)/g, respectively. As the activation time increased, the fraction of micropores decreased from 85% to about 40%. On the other hand, the porosity of the mesopores increased to about 60% from a ratio of about 10%. The specific power adsorption has been increased with the development of the mesopores and exhibited 20 960 sK/g at APHC-10-5 (540% higher compared to that of APHC-10-2). It was confirmed that capacity of n-butane and the pore characteristics of the ACs was determined by pore the 5 correlation between the adsorption diameter of 1.5-4.5 nm.