Carbon nanofiber (CNF) based buckypaper was explored as a potential thermal interface material (TIM) for electronics. CNFs were subjected to heat treatment temperatures of 1100 °C, 1500 °C and 3000 °C. TIMs were prepared and characterized using thermal impedance test stand. Results show that the thermal impedance at the interface decreased in conjunction with the increasing heat-treatment temperature of CNFs. TIMs with graphitized CNF exhibit a significant decrease of 54% in thermal impedance in comparison with the dry contact. This improvement is likely due to the high degree of CNF graphitizibility and the resulting outstanding electrical and thermal conductivities.