Aluminum oxy-nitride (AlON), a solid solution in the binary phase diagram of Al2O3-AlN, is a relatively new spinel type material. In the present study, the optimum sintering agent and sintering conditions of AlON were determined and a sintering process was carried out using spark plasma sintering (SPS) techniques. An X-ray diffraction phase characterization of samples showed that the amount of the AlON phase in the Mg-doped was greater than that of the Dy-doped sample. The second part of study, focused on Mg-doped compositions to investigate the optical properties of the samples A correlation between process and performance was studied in detail using SEM, XRD, FTIR characterization techniques. To increase the amount of the AlON phase and to improve the optical properties, some of the samples were selected and heat treated under inert atmosphere. After the heat treatment results, it was seen that second phases were eliminated and higher transparency was obtained for the Mg-doped samples. (C) 2015 Elsevier Ltd. All rights reserved.