Bio-based PCMs are a type of organic fatty acid ester PCMs made from natural resources, such as soy beans and palm oils. Bio-based PCMs are capable of absorbing, storing, and releasing large amounts of latent heat, similar to conventional paraffin-based PCMs. Compared to the paraffinic PCMs, Bio-based PCMs are significantly less flammable. Also they have a major drawback, namely the low thermal conductivity like as the other PCMs. To improve the thermal conductivity of Bio-based PCMs, xGnP (Exfoliated graphite nanoplatelets) can be an effective enhancement. Therefore we prepared form stable Bio-based PCMs with xGnP, by using the vacuum impregnation method. In this study, we used one of the Bio-based PCMs, which contained soybean oils, coconut oils, and beef tallow. And it has a latent heat capacity of 149.2 J/g and melting point of 29.38 degrees C. The Bio-based PCM was incorporated into the porous structure of xGnP. The characteristics of the Bio-based composite PCM were determined by using SEM, DSC, MR, TGA and TCi. (C) 2013 Elsevier B.V. All rights reserved.