The degradation behavior of an elastomeric polyurethane (PU) was investigated with accelerated ultraviolet (UV) and hydrothermal (HT) techniques. Samples were subjected to UV exposure and HT conditions for 3 or 5 months and were removed in 1-month intervals from the test chambers. Their chemical structure was evaluated with Fourier transform infrared (FTIR) spectroscopy. The thermal transitions of the aged samples were evaluated with differential scanning calorimetry (DSC). Both FTIR and DSC results showed no evidence of significant structural damage to the HT-aged PU throughout exposure. FTIR analysis of the UV-aged samples showed a noticeable change in the chemical structure of the polymer after 1 month of UV exposure. The results from DSC correlated with the FTIR analysis of the UV-aged samples. Spectroscopy and thermal analysis of the aging of the PU samples were correlated to mechanical analysis. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110:712-718, 2008