Montmorillonite-acrylamide intercalation compounds were prepared by treating sodium montmorillonite with acrylamide aqueous solutions, the concentrations of which were varied from 4% to 20%. The basal spacings of the compounds prepared from 4% and 20% acrylamide aqueous solutions were ca. 15 Å and 20 Å, respectively. These values suggested that acrylamide was intercalated as monomolecular and bimolecular arrangements in the interlayer space of montmorillonite with the molecular plane perpendicular to the silicate sheet. After the removal of excess acrylamide by washing with nonpolar organic solvents, the intercalated acrylamide was polymerized to form montmorillonite-polyacrylamide intercalation compounds. These compounds absorbed more water than raw sodium montmorillonite.