Adsorption of methanol, ethanol, n-propanol, and n-butanol by Pocahontas No. 3, Upper Freeport, Illinois No. 6, and Beulah-Zap Argonne premium coals was investigated to clarify the effect of alkyl group bulk on adsorption and to evaluate the micropore and cross-linked structure of coals. A strong steric effect was found for all coals. The sorption isotherms could be fitted to the Langmuir-Henry dual-mode equation, and the total sorption could be divided into adsorption and diffusion (dissolution) components, which were separately estimated. For all coals, the Henry's law constant k(D) decreased as the size of substituted group increased in the order methyl < ethyl < propyl, and the k(D) for n-butanol was similar to that for n-propanol. There was a significant decrease for the high-rank Pocahontas No. 3 and Upper Freeport coals. In contrast, the k(D) for the Upper Freeport extraction residue was quite large for all alcohols, compared to those of the raw coal, although the pore saturation constant was not greatly affected. The increase in k(D) for the residue is mainly the result of an increase in the physical diffusion sites (voids) formed by extraction.