Two kinds of phase change materials (PCMs) were prepared anti various characterization techniques were employed to investigate the influence of preparation methods on the structural characteristics and thermal properties. The results show both composites have similar morphology, structure and comparable latent heats with SA intercalated into a-MMT gallery. Thermal reliability and thermal cycling test obviously indicated that preparation technology affected the thermal properties. Latent heat of the composite prepared by melting impregnation method changed by -0.59% for fusion and -1.01% for solidification, whereas, it declined by 39.71% and 40.89% for the composite prepared by solution immersed technology after 600 thermal cycling. In other words, the melting impregnation method is a potential candidate for preparing reliable composite PCMs. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.