Abstract—The conditions and kinetics of yttrium aluminum garnet (YAG) crystallization from an X-ray amorphous mixture of hydrated yttrium and aluminum compounds (with a stoichiometric yttrium to aluminum ratio) containing various functional groups have been studied by simultaneous thermal analysis, and temperature variations of the composition of conversion products have been monitored by X-ray diffraction. The technique used to analyze nonisothermal differential scanning calorimetry data in order to assess parameters and gain detailed insight into the mechanism of YAG formation can serve as a basis for predicting temperature and time conditions of formation of not only YAG but also other functional crystalline phases in designing modified and novel ceramic and glass-ceramic materials.