Thermal decomposition studies of intimate mixtures of different molar ratios of potassium nitrate and chromium(III) oxide were made by employing thermogravimetry differential thermal analysis, chemical analysis, infrared spectral measurements and X-ray powder diffraction patterns. Potassium nitrate in the presence of chromium(III) oxide starts decomposing around 350°C which is much below the decomposition temperature of pure potassium nitrate. Chromium(III) is completely oxidized into its hexavalent state when the mole ratio of KNO3 to Cr2O3 is greater than three. © 1976.