The development of advanced photocatalytic materials for environmental purposes is among the high research topics. In the present work, a nanocomposite BiOCl@Kaol, made of kaolinite supported Bismuth Oxychloride “BiOCl” photocatalyst, was designed for Rhodamine B dye photodegradation in aqueous solution. The obtained BiOCl@Kaol nanocomposite exhibited high photocatalytic activity in the removal of Rhodamine B dye (RhB) from water, with a degradation efficiency reaching 100 % within 35 min. Furthermore, it was observed that the nanocomposite photocatalyst, BiOCl@0.4Kaol, at optimal Clay/BiOCl ratio of 0.4, exhibited 4.37 times better photocatalytic performance, compared to bare BiOCl. Finally, to elucidate the photodegradation mechanisms, we determined various interactions occurring between BiOCl and kaolinite particles, as well as between RhB molecules and BiOCl@Kaol nanocomposites, using Monte Carlo calculations. It was concluded from Monte Carlo calculations that hydrogen bonds were established between oxygen atoms of BiOCl and H of kaolinite (001) hydroxyl groups upon the adsorption of BiOCl (003) particles on the kaolinite (001) surface, owing to its high negative interaction energy. Meanwhile, van der Waals attraction was also established between the RhB molecules and the BiOCl@Kaol (001) surface.