The thermal decomposition behaviors of 4,4'-azo-bis(1,2,4-triazolone) (ZTO) and its salts were investigated for the first time by using accelerating rate calorimetry. Based on the experimental results, the kinetic parameters of exothermic reaction of ZTO and its salts were calculated. The thermal decomposition parameters, including the initial decomposition temperature, the adiabatic temperature rise rate, were obtained from the thermal inertia factor. The adiabatic experiment revealed that ZTO and KZTO·H.sub.2O both had a relatively high initial exothermic decomposition temperature at 230.6 and 235.6 °C, respectively. The maximum self-heating rate of exothermic process of ZTO was 105.9 °C min.sup.-1 (at 248.7 °C), which meant that ZTO decomposed very fast. In addition, the reaction order, apparent activated energy (E.sub.a), and pre-exponential factor (A) were also calculated.