Octadecylenetrimethylammonium-montmorillonite as an organophilic montmorillonite intercalations complex was formed by cation exchange reaction between Na-montmorillonite and 9-octadecylenetrimethylammonium cation. After drying of this organophilic montmorillonite at $65^{circ}C$ in high vacuum, the complexes were reacted with various swelling-solutions such as benzene, toluene, o-xylene, pyridine, $alpha$-picoline, 2-ethyl-pyridine, 2-vinyl-pyridine and styrene, and the corresponding basal spacing obtained were 43.9$AA$, 54.3$AA$, 51.7$AA$, 41.5$AA$, 42.5$AA$, 39.9$AA$, 39.8$AA$, 44.8$AA$, respectively.