The sulphation process of pre-calcined limestone illustrates the application of programmed thermal analysis techniques using different gas sequences. The direct usage of commercial equipment (e.g. Derivatograph and Mettler thermoanalysers) is limited because the thermobalance unit must be additionally isolated to operate under a corrosive gas atmosphere. The TA methods are capable of predicting the behaviour of the potential sorbents towards SO2/SO3 in a larger scale installation. The thermal stability of the compounds from the Ca-S-O system and the influence of additives on sulphation have been found useful in elucidation of the limestone sulphation mechanisms. The thermoanalytical investigations had to be supplemented by independent complementary techniques such as X-ray diffraction, scanning electron microscopy with backscattered electron image followed by quantitative energy dispersive X-ray microanalysis.