The thermal stability of the eutectic LiNO3-NaNO3-KNO3 salt was investigated by simultaneous differential scanning calorimetry, thermogravimetry and mass spectrometry (DSC/TG-MS). The work was carried out between room temperature and 1000 degrees C in blanket gas atmospheres of argon, nitrogen, oxygen and air. The stability of the salt, as measured by the gases evolving from the melt, was influenced by the atmosphere. Evolution of the main gaseous species NO was detected at 325 degrees C in an atmosphere of argon, at 425 degrees C in an atmosphere of nitrogen, at 475 degrees C in an atmosphere of air and at 540 degrees C in an atmosphere of oxygen. Prior to melting, the eutectic underwent endothermic (alpha/beta) solid-solid type transformation at 87 degrees C. The melting point was 121 degrees C, and the solidification point 98 degrees C. Under-cooling of the salt coincided with the onset of the (alpha/beta) solid-solid transformation upon heating. At a temperature of 500 degrees C in air, TG analysis showed that the long-term stability of the salt was limited and this was confirmed by DSC. Uncertainty analysis indicated that the measurement of temperature is accurate to +/- 2.7 degrees C. (C) 2013 Elsevier B.V. All rights reserved.