This master thesis investigates the volatilization behavior of indium during a pyrometallurgical treatment. Therefore, indium oxide was reduced by means of carbon and selectively volatilized by using a suitable chlorine compound. In this context the reaction partners, mass losses, velocities and external influences were determined and evaluated. The first investigations include experiments in a laboratory furnace for the evaluation of the appropriate chlorine carrier. The use of calcium chloride resulted in a higher mass reduction in the reaction mixture than sodium chloride. Thermal treatments in a differential thermal analysis (DTA) were used to detect the partial reaction steps of the process. The resulting diagrams show the influence of the purging gas and the behavior of the pure substances and the reaction mixture. The final calculations by means of a chemical reaction and equilibrium software (HSC Chemistry) compared the obtained results from DTA with thermodynamic data. These experiments showed that it is possible to volatilize indium by using the chlorine carrier calcium chloride to a high degree. In future, findings from these investigations can form the base for treating an indium-containing residue, such as jarosite from hydrometallurgical zinc production, in a similar way.