This paper deals with the thermal performances of shape-stabilized phase change materials (SSPCMs) for energy saving in various fields. Two SSPCMs were prepared by impregnating coconut oil and palm oil, as phase change materials (PCMs), into exfoliated graphite nanoplatelets (xGnP), as a supporting material. Coconut oil and palm oil are types of organic fatty acid ester PCMs made from under-used and renewable feedstocks. However, they have a major drawback, namely their low thermal conductivity. To improve the thermal conductivity of organic fatty acid ester PCMs, xGnP can be effective. Therefore we prepared form-stable organic fatty acid ester PCMs with xGnP, using the vacuum impregnation method. In this study we used coconut oil and palm oil, which have latent heat capacities of 110.4 and 127.3 J/g and melting points of 26.78 and 17.26 degrees C, respectively. The organic fatty acid ester PCMs were incorporated into the porous structure of xGnP. The thermal conductivity of the produced SSPCMs were over 400% higher than pure fatty-acid ester PCM. Also, the latent heat were 82.34 and 77.18 J/g, respectively. The characteristics of the organic fatty acid ester PCMs were determined by using SEM, DSC, FT-IR, TGA and TCi. (c) 2015 Elsevier B.V. All rights reserved.