A pyrometallurgical route for the synthesis of magnesium aluminate spinel by thermal treatment of a mechanical mixture containing 29 wt% MgO (periclase) and 71 wt% Al2O3 (alumina) in chlorine atmosphere was developed and the results were compared with those obtained by calcining the same mixture of oxides in air atmosphere. Isothermal and non-isothermal assays were performed in an experimental piece of equipment adapted to work in corrosive atmospheres. Both reagents and products were analyzed by differential thermal analysis (DTA), X-ray diffraction (XRD) and X-ray fluorescence (XRF). Thermal treatment in Cl-2 atmosphere of the MgO-Al2O3 mixture produces magnesium aluminate spinel at 700 degrees C, while in air, magnesium spinet is generated at 930 degrees C. The synthesis reaction of magnesium aluminate spinel was complete at 800 degrees C. (C) 2014 Elsevier Ltd. All rights reserved.