Multiwall carbon nanotubes at various concentrations up to 1 wt% were dispersed in thermoplastic polyurethane using a laboratory internal mixer at 200 ºC and 60 rpm. A control sample of the neat polymer was prepared under similar conditions. The nanocomposites were characterized in terms of thermal behavior, tensile and dynamic mechanical properties and thermal and electrical conductivity. The Young’s modulus, tensile strength, thermal degradation temperature and storage modulus at high temperature increased with carbon nanotube (CNT) concentration up to 0.3 wt% (0.22 vol. %). This concentration may be regarded as the thermo-mechanical percolation threshold, in accord with the theoretical percolation threshold calculated based on the classical percolation theory for fillers with similar aspect ratio to be 0.32 vol. %. At CNT concentrations of 0.7 wt% and higher, a decrease in thermo-mechanical properties was observed. Deterioration in properties was explained in terms of changes in the CNT dispersion state and aggregate formation as confirmed by SEM micrographs. Nanocomposites with 0.3 wt% CNT showed also the highest tanδ at glass transition temperature and lowest damping at temperatures as high as 175 ºC. The nanocomposites were also characterized for their electrical and thermal conductivities.