The process of roasting marmatite and marmatite concentrate was investigated experimentally. Results obtained by DTA under non-isothermal conditions were used for determining kinetic parameters for the oxidation process in the system Zn-Fe-S by using Kissinger and Ozawa methods. The activation energy for the marmatite concentrate oxidation process is 187 and 194 kJ/mol, according to the Kissinger and Ozawa methods, respectively. In the case of the pure mineral marmatite, the corresponding values for activation energy are 69 and 86 kT/mol. Mineralogical characterization was done by X-ray analysis, which enabled determination of the phases that were present during the oxidation process.