Interactions between five Argonne Premium coals (Pocahontas No. 3, Upper Freeport, Pittsburgh No. 8, Illinois No. 6, and Beulah-Zap) and various organic compounds were studied using an inverse liquid chromatography (ILC) technique in which coals were used as the stationary phase. The capacity factors (the increment of the elution volume of the probe relative to the elution volume of the carrier solvent) of organic compounds were determined using acetonitrile, toluene, and methanol as the carrier solvents. Low-rank Beulah-Zap and Illinois No. 6 coals had relatively high capacity factors for alcohols and other polar compounds, but the high-rank Pocahontas No. 3 coal had relatively high capacity factors for nonpolar compounds such as n-hexane and carbon disulfide. The capacity factors for all coals were affected by the increasing steric bulk of butyl alcohol isomers; the effect was most pronounced for lower-rank coals. The steric effect had two sources: steric hindrance of penetration into the micropores of coal, and the effect of bulk on the conformation between the interacting sites in coal and the isomers. Data suggest that the micropores in high-rank coals Upper Freeport and Pocahontas No. 3 coals have diameters of 4-7 Angstrom.