Sorption isotherms of N-2 and CO2 were detd. at 77.5 and 293 K, resp., on 65-85% C bituminous coals (type 32) in relation to particle size (0.063-0.075, 0.075-0.125, 0.1250.25, and 0.25-0.355 mm), volatiles, and origin. N-2 sorbed only on the external surface, at best on the 0.063-0.075mm grade (1.18-3.53 m(2)/g in sp. surface). CO2 penetrated very easily into the micro and submicro porous structure (so that it could displace other gases, e.g. CH4 and thus enabled the micropore vol. and the sp. surface of the coals to be detd. The porous structure was as accessible to CO2 as it was to H2O and MeOH.