The thermal decomposition of amisulpride was studied by simultaneous thermogravimetry/derivative thermogravimetry (TG/DTG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). The influence of the heating rate (5, 10, 15 and 20 °C min−1) on the TG was verified. For the determination of kinetic parameters from the TG/DTG curves, the following methods were utilized: Arrhenius equation, Coats–Redfern, Horowitz–Metzger, Flynn–Wall–Ozawa and Starink methods. The activation energy obtained was found to be about 108 kJ mol−1. Drug purity and melting point were determined by Van’t Hoff equation. The results were in agreement with the recommended pharmacopoeia.