New results are presented on the thermal stability of the primary explosive, the potassium salt of 4,6-dinitrobenzofuroxan (KDNBF) and on the mechanism of its decomposition. The new work complements and extends previous work done in our laboratory. The thermal decomposition of KDNBF has now been studied using a wide variety of experimental techniques: differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), accelerating rate calorimetry (ARC), heat flow calorimetry (HFC) and simultaneous thermogravimetry-differential thermal analysis (TG-DTA). The latter technique is coupled in our laboratory to FTIR and mass spectrometers to provide a very powerful method where the reaction products, the mass change and the temperature difference between the sample and reference can be monitored simultaneously as the material is decomposed. The results demonstrate that the decomposition takes place by a multi-step exothermic process directly from the solid state. The initial decomposition process does not appear to depend on the nature of the atmosphere, or the total pressure. The main gaseous product of the decomposition is carbon dioxide, with water, nitrous oxide and cyanogen also being formed. Kinetic parameters measured for the decomposition using a number of different techniques are in good agreement over eight orders of magnitude. An average of the available data gives: ln(k/min(-1)) = (41.2 +/- 5,7) - ((170 +/- 22) kJ mol(-1))/RT Although sensible Arrhenius data were generated, it was demonstrated that the mechanism of the decomposition is far from simple. For example, if KDNBF is thermally aged, its onset temperature can be decreased significantly, demonstrating that substantial changes to the material can occur well below its apparent decomposition temperature. The sensitivity of KDNBF to impact, friction and electrostatic discharges was also established. The results are compared to those available in the literature for KDNBF and for other primary explosives. Crown Copyright