In this paper, multi-walled carbon nanotubes (CNT) were dispersed in D-Mannitol to prepare enhanced thermal conductive nanocomposites phase change materials (PCM) with 0.1% and 0.5% weight fraction. The PCM were tested for 100 thermal cycles and characterized by using techniques such as Differential Scanning Calorimetry (DSC), Thremogravimetric analyser (TGA) and Fourier Transform Infrared (FT-IR). The effect of adding CNT on energy storage/release performance of DM was experimentally studied. Maximum thermal conductivity enhancement was found to be similar to 7% and similar to 32% respectively for 0.1-0.5 wt.% DM-CNT composites. It was observed from the crystallization kinetics study of DM that addition of CNT resulted in lowering the crystallization of DM. However after thermal cycling, the latent heat capacities decreased yet showed a high latent heat enthalpy of 241.16 kJ/kg. Experimental results showed that the total time for complete cycle reduced by similar to 25.7% for 0.5 wt.% DM-CNT. The analysis of the experimental results indicate that the proposed PCM nanocomposites exhibit excellent thermal and chemical stability with enhanced heat transfer characteristics. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.