[EN] The dielectric relaxation behavior of segmented polyurethane has been studied using Broad-Band Dielectric Spectroscopy in the frequency domain, 10(-2) to 10(8) Hz, and in the temperature range of -120 to 140 degrees C. The spectra show three secondary processes (, , and ) followed by the relaxation and conductive processes. The Havriliak-Negami (HN) phenomenological equation was used in order to characterize all the processes. The , , and relaxations are probably associated with (i) local motions of the main chain (ii) motions of the carbonate group in the soft phase and (iii) reorientational motions of water molecules. The microphase separated morphology associated with soft and hard domains is reflected in the dielectric spectra, at high temperatures, by the presence of the Maxwell-Wagner-Sillars (MWS) interfacial polarization process. This work was financially supported by the DGCYT through Grant MAT2012-33483. The authors thank UBE Chem. Corporation for supplying the polycarbonatodiol to synthesize the polyurethanes of this work. Ortiz Serna, MP.; Carsí Rosique, M.; Redondo Foj, MB.; Sanchis Sánchez, MJ.; Culebras, M.; Gomez, CM.; Cantarero, A. (2015). Thermal and dielectric properties of polycarbonatediol polyurethane. Journal of Applied Polymer Science. 132(22):42007-1-42007-8. https://doi.org/10.1002/app.42007