The thermal decomposition of 4,4’-diaminodiphenylsulphone (DDS) was studied by thermogravimetry, differential scanning calorimetry and thermal volatilisation analysis. Solid residues, high-boiling and gaseous products of degradation were collected at each step of thermal decomposition and analysed by infrared spectroscopy and gas chromatography/mass spectrometry. On programmed heating at normal pressure, DDS starts to evaporate at 250 degrees C. Thermal decomposition, which probably proceeds through homolytic scission of the S-C bond is simultaneously observed, The resulting sulphonyl radicals provoke polymerisation and cross-linking of the solid residue which undergoes a limited degradation at 350 degrees C with elimination of heteroatoms N and S as volatile moieties. Above 400 degrees C, the residue undergoes a complex charring process leading to an aromatic char typical of carbonised aromatic polymers.