Abstract In this paper, investigations have been carried out on electron beam irradiated thermoplastic and aromatic polyurethane (PU). The changes in chemical structure after irradiation were determined using FTIR spectroscopy. This study has allowed us to highlight polymer degradation versus depth and dose by following the decrease in the NH-bond intensity. The PU oxidation was also studied by following the appearance of OH bonds. Results showed that degradation and oxidation of the PU reaches a maximum between 150 and 250 μm. These effects are quantifiable up to 500 μm. Experimental results were compared with the distribution of the energy deposition simulated by the EGS4-PRESTA code. Our experimental results are in strong accordance with the simulation.