In this paper, the chlorination of In2O3 has been studied using gaseous chlorine as chlorinating agent. The results of the thermodynamic analysis for the reaction of In2O3 chlorination indicate that this reaction is possible throughout the entire studied temperature range. The progress of the chlorination was followed measuring the mass changes for isothermal and non-isothermal experimental assays. The effect of temperature, reaction time, flow rate and partial pressure of Cl2 was investigated. The solids were characterized by scanning electron microscopy (SEM) and X-ray diffractometry (XRD). The results of the chlorination assays showed that the reaction between In2O3 and Cl2 starts approximately at 400°C, with a mass loss of 50% at 620°C, and that, for temperatures between 500 and 650°C, the reaction rate increases along with the reaction temperature. The calculated values for the apparent activation energy and for the order of reaction were 125.5kJ/mol and 0.91, respectively. The model 1−(1− α)0.4 = Kt is the best represents the experimental data.