SnO2.xH(2)O was incorporated into the silicate layers of Namontmorillonite (SnO2.xH(2)O-Mont) via the hydrolysis of (NH4)2SnCl(6) in an aqueous slurry of Na-montmorillonite (Mont). The air-dried material and samples treated at various temperatures were characterized by X-ray diffractometry, X-ray fluorescence and infrared spectroscopies, derivatography and BET measurements. It was found that partially hydrated SnO2 was precipitated inside the silicate layers. Upon heat treatment dehydration/ dehydroxylation occurred, thus, the strength of hydrogen bonding holding the introduced substance in the layered structure decreased. From 393 K the SnO2 started to migrate onto the outer surface and above 673 K finely dispersed, day-supported SnO2 was formed.