Fatty acid phase change materials (PCMs) have some advantages such as less corrosivity, no separation of subcooling phase and low price. In this paper, capric acid and palmitic acid are composited according to a certain mass ratio to prepare binary fatty acid. Capric-palmitic acid are absorbed into attapulgite by vacuum method to prepare capric-palmitic acid/attapulgite composite PCMs. Analysis methods such as differential scanning analysis (DSC), scanning electron microscope (SEM), Fourier transform infrared (FT-IR) and specific surface analysis (BET method) are used to test the thermal properties, structure and composition of the prepared composite PCM. The results indicate that the pore structure of the caplic-paltimic acid/attapulgite composite PCM is open-ended tubular capillary, which is beneficial to the adsorption. Capric acid and palmitic acid can be absorbed uniformly into attapulgite and the optimum absorption ratio of capric-palmitic binary fatty acid is 35%. There is no chemical reaction between the capric-palmitic acid and attapulgite. The phase change temperature of the capric-palmitic acid/attapulgite composite PCM is 21.71 degrees C and the latent heat is 48.2 J/g. (C) 2011 Elsevier Ltd. All rights reserved.