DTA curves of synthesis lead sulfide and commercial. lead concentrates during oxidation were measured to clarify the mechanism of ox- idation of lead sulfide. The oxidation reac tions could be divided to elementary reactions with production of basic lead sulfates such as 2PbO PbSO4. An existance of iron sulfide played an important role of the oxidation of lead concentrates. The oxidation rates of lead sulfide were measured in the wide range of oxygen potenti- als using IR type SO2 gas-meter. The oxidation rates under low Po 2 which corresponds to the direct oxidation smelting were much lower than those obtained under high Pot. The combustion temperatures of lead sulfide were also measured by hot thermocouple method. Those values were extremly low compar- ing the oxidation temperatures obtained by DTA.