This work presents the thermal property study of single wall and multi wall carbon nanotubes (SWCNT and MWCNT) both in their purified and unpurified forms introduced to silicone elastomer to enhance the thermal diffusivity of this industrial polymer. An increase in thermal diffusivity was observed for incremental loading of both purified and unpurified single wall and multiwall CNT in epoxy at different percentages. An increase of thermal diffusivity as high as 130% was achieved for ∼2 wt% loading of both single wall and multi wall nanotubes. Electrical conductivity measurements showed a percolation threshold for 2% loading of multiwall CNT, below which the nanotube-epoxy composite behaved as an insulator — this is a key property for applications where electrical isolation is required. For single wall CNT-epoxy composite all the samples showed high resistance to the conduction of current. Thermal impedance measurements showed a strong dependency of contact resistance with percentage loading. Finally, the feasibility of deploying carbon nanotube-polymer composites as practical thermal interface materials for electronics thermal management is discussed.