Three Japanese coals of different rank were heat-treated with KOH from 300℃ to 850℃, and their changes in pore structure were estimated by the adsorption of nitrogen at -196℃, X-ray diffraction patterns and TEM photographs of them. Furthermore, twelve Japanese coals were KOH - activated only at 800℃, and their variations in pore structure with rank of coal were studied by the N_2 adsorption experiments.
