Je-chun clay, Hwa-soon bentonite, and Hwa-soon montmorillonite were treated with treated with organic solvents, i.e., ethylene glycol, ethanol, n-hexane, dioxane, ethylene chlorohydrin and obtained X-ray diffractograms were compared with those of the original samples. Organic solvent was adsorbed on the basal plane surfaces of Je-chun clay, Hwa-soon bentonite, Hwa-soon montmorillonite and, as a result, the axis spacing ws increased, However, organic solvent did not affect the non-expanding lattice of Japanese acid clay and the basal plane remained unchanged.