This study analyses pyrite (FeS2) roasting in a temperature range of 400–500°C, with partial oxygen pressure from 1·01 to 28·60 kPa and particle size between 12·3 and 33·0 μm, using thermogravimetric methods. The pyrite oxidation rate was significantly influenced by temperature, partial oxygen pressure and particle size. Pyrite oxidation kinetics was also analysed, and the model X=kt gave a good description of the reaction kinetics. The dependency of pyrite oxidation on partial oxygen pressure was in the order of 3/5. The intrinsic oxidation rate constants were also determined and an activation energy value of 60·5 kJ mol−1 was obtained for the temperature range used in the study. The results indicate that the rate of pyrite oxidation was controlled by chemical reactions under the conditions of the experiments.