Methodology of investigation of heat resistance of composite ceramic materials based on aluminium nitride in air in wide temperature range has been developed. Absolute error of measuring the mass of specimen has been not more than 0.17 g in this case. Study of interaction between composite materials based on aluminium nitride and phosphate binder has been performed. Mechanism of influence of the binder nature on kinetics of process of oxidation has been determined. Relatively low values of activation energy makes it possible to believe that rate of the oxidation process is determined by diffusion of aluminum atoms through α-Al2O3 film.