Azodicarbonamide (ADCA) is a well-known chemical blowing agent used in the fabrication of polyolefin foams which decomposes into gases at temperatures above the melting temperature of the polymer. In these polymer foams, the polymer is usually crosslinked before or during the foaming process to increase its viscosity and make it capable of supporting the pressure of the gas during foaming. This crosslinking process allows producing low-density foams with homogeneous cellular structures. A typical procedure to crosslink the polymer is to irradiate it using a high energy-electron beam. When ADCA is incorporated into the polymer before the irradiation process, it is also exposed to the high energy electron beam. However, the effect of the irradiation on the decomposition process of ADCA has not been explored yet. In this research, it has been found that there is a reduction of the thermal decomposition temperature of ADCA when this material is electron irradiated with different doses ranging from 25 to 150 kGy, being this reduction higher when the irradiation dose is increased. It has also been found, that the reduction of the decomposition temperature is due to a modification of the lattice parameters of the crystalline structure of ADCA. POLYM. ENG. SCI., 59:791-798, 2019. (c) 2018 Society of Plastics Engineers