We study ionic structure of KNO3–NaNO2 melts under air atmosphere by using Raman spectroscopy. Molar fraction of NO3- and NO2- is obtained and thermal stability of this kind of melts system is then analyzed. The results show that when the temperature is increased to a certain value, equilibrium between the decom-position of NO3- and the oxidation of NO2- exists in KNO3–NaNO2 melts. When temperature is higher than 644 K, the molar fraction of NO3- decreases a little with temperature increasing fo
