A fully transparent aluminum oxynitride (ALON) was prepared using microwave reacting sintering. A home-made 1.5 Kw, 2.45 GHz single mode microwave applicator was used to perform microwave sintering in flowing pressure nitrogen at ambient pressure. X-ray diffraction (XRD) was used to analyze the phase composition of the ALON samples. The microstructural development of the microwave sintered ALON samples was studied using an optical microscope.