A kaolinite-pyridine intercalation compound was prepared using hydrated kaolinite as an intermediate. Hydrated kaolinite having a basal spacing of l0/~ was treated with pyridine to form a well- ordered intercalation compound having a basal spacing of 12.0/k. Infrared spectroscopy indicated the presence of hydrogen bonding between the hydroxyls of the kaolinite and the pyridine. 29Si nuclear magnetic resonance spectroscopy with cross polarization and magic-angle spinning revealed that inter- calated pyridine affected the environment of silicon. The mono-substituted pyridine derivatives were also intercalated with hydrated kaolinite. On the basis of the basal spacings of the intercalation compounds and the stabilities of the derivatives between the layers, the pyridine appeared to be in an approximately perpendicular position, with the nitrogen facing the gibbsitic sheets.