A polyazido compound, 1,3-di(azidoacetoxy)-2,2-di(azidomethyl)propane (PEAA) was synthesized and identified. Thermal properties of PEAA, such as the glass transition temperature (T,), differential scanning calorimetry (DSC) and thermogravimetric analysis (DTG) were investigated in detail. Two steps in the course of thermal decomposition of PEAA were observed clearly, and some gases carbon monoxide, carbon dioxide, nitrogen, hydrocyanic acid, methane and 2-methyl-1,3-butadiene were identified as decomposition products by in situ cell FTIR. The pyrolysis mechanism was also proposed.