DTA is used in the study of organo-clay complexes. Curves are recorded either in oxidizing or reducing environments. For the interpretation of the different peaks DTA is usually supplemented by TG and in recent years also by EGA. Most DTA curves can be divided into three regions: (I) the region of the dehydration of the clay; (II) the region of the reactions of the organic matter and (III) the region of the dehydroxylation of the clay. An oxidizing environment results in intense exothermic peaks whereas a reducing environment results in small broad endothermic peaks. Consequently, most investigations were carried out in the presence of air. The characteristic features of the exothermic peaks and the different applications of the method are discussed.