Tonsil, a bentonitic clay, has long been employed as a Brönsted & Löwry and Lewis acid catalyst, reagent and/or support of various inorganic reagents. In this sense, this review deals with a detailed characterization of the clay, in addition to his major uses covering de complete information from 1981 through 2003, which was the result of considerable proliferation of papers from our and other laboratories.

Thus, in order to understand the behavior of the clay, several structural and surface properties determinate by means of various analytical techniques are discussed: ²⁹Si and ²⁷AL MAS-NMR; X-ray diffraction; Scanning electron microscopy (SEM); IR-Spectrophotometry; thermal analysis (DTA and TGA); as well as a N₂ adsorption technique (BET)

Moreover, and as it can be seen, the aim of the review is to highlight the use of Tonsil in the area of heterocyclic molecules; this in complement with some other interesting features.