In this research [RCOOH]-$varepsilon$-Caprolactam-Montmorillonite was synthesized by reaction between Na-Mont-morillonite (10-Carboxy-n-decyl)dimethylethylammonium (=RCCOH) ion and $varepsilon$-Caprolactame-Motmorillonite ob-tained was 3.62$AA$ After heat treatment of this intercalations complex at 37$^{circ}C$ in high vacuum for 12 h 24 h, 40 h and 90 h the basal spacing was reduced to 35.8$AA$, 34.2, 17.5 $AA$ and 16.6$AA$ respectively. The calculated amount of free $varepsilon$-caprolactame included int he intercaltions complex and that of $varepsilon$-caprolactame which is interca-lated into the interlayer space of montomorillonite and still remained after heat treatment are 4.6~4.9 and 0.5 molecules per unite cell of montmorillonite respectively.