Segmented polycarbonatediol polyurethane (PUPH) has been synthesized and modified with different amounts of graphite conductive filler (from 0 to 50 wt%). Thermal and dynamical thermal analysis of the composites clearly indicates changes in the polyurethane relaxations upon addition of graphite. Broadband dielectric spectroscopy has been used to study the dielectric properties of the (PUPH) and one composite in the frequency range from 10−2 to 107 Hz and in the temperature window of −140 to 170 ◦C. Relaxation processes associated with different molecular motions and conductivity phenomena (Maxwell–Wagner–Sillars and electrode polarization) are discussed and related to the graphite content We acknowledge the financial support of the Ministry of Finances and Competitiveness through the Grant CDS2010-0044 belonging to the "Consolider-Ingenio Programme" and for the Grant MAT2012-33483. The authors thank UBE Chem Eur for the PCD supply for this work.