A 0.5-1.0-mm flame coal was oxidized in air at 200 and 250 degrees C for 5, 40 and 70 hrs. (final ratio O/C ca. 0.3) and carbonized 5 degrees C/min in Ar up to 850 degrees C. Meso (2-50), micro (0.4-2) and submicropores (< 0.4 nm( were detd. by the C6H6 and CO2 adsorption methods. At either temp. of oxidation the O/C and H/C ratios in coal varied within 5-40 hrs. extensively and over 40-70 hrs. slightly. For the coal oxidized at 200 degrees C, the porous structure was hardly affected (total micropores vol., 50 mm(3)/g; only submicropores vol. increased over 540 hrs.). In coal oxidized at 250 degrees C the total vol. of micropores rose (Up to go mm(3)/g) and wider micropores (0.4-2 nm) developed. Mesopores vol. rose only in coal oxidized for 70 hrs. at 250 degrees C. The porous structures of the chars prepd. from the original and midly oxidized (5 hrs./200 degrees C) coal were practically identical, whereas those formed in chars prepd. from higher-oxidized coal were characterized by a greater total micropores vol. (at 200 degrees C mainly submicropores but at 250 degrees C micropores developed).