Thermal performance of nanocomposite carbon nanofibers filled paraffin wax was studied experimentally and analytically. The transient temperature response of made nanocomposite was measured during its solidification process and the cooling rate was predicted. It was found that nanocomposite thermal conductivities were enhanced significantly causing the cooling rate to increase. An analytical model was introduced based on one-dimensional heat conduction approach to predict the effective thermal conductivity for the new nanocomposites and its findings showed good agreement with the experimental data. Also, a comparative study was performed to investigate the effect of carbon nanofibers surface characteristics on thermal performance of paraffin wax.