The preparation, characterization and modification of eutectic hydrate salt (CaCl2 center dot 6H(2)O-MgCl2 center dot 6H(2)O) as a new phase change material (PCM) were investigated in this paper. CaCl2 center dot 6H(2)O was prepared using industrial grade calcium chloride (CaCl2), and then 10, 15, 20 and 25 wt% MgCl2 center dot 6H(2)O was added into CaCl2 center dot 6H(2)O respectively in order to obtain CaCl2 center dot 6H(2)O-MgCl2 center dot 6H(2)O eutectic hydrate salt PCM. The modification of CaCl2 center dot 6H(2)O-25 wt% MgCl2 center dot 6H(2)O material was designed by a uniform experimental Method to select the efficient nucleating and thickening agents. The results show that SrCl2 center dot 6H(2)O and SrCO3 can be effective nucleating agents, and hydroxyethyl cellulose (HEC) is an excellent thickener. For CaCl2 center dot 6H(2)O-25 wt%, MgCl2 center dot 6H(2)O material with 3 wt% SrCl2 center dot 6H(2)O, 1 wt% SrCO3 and 0.5 wt% HEC, the supercooling is reduced to 2 degrees C, and its phase change temperature and latent heat are 21.4 degrees C and 102.3 J/g, respectively. (C) 2014 Elsevier B.V. All rights reserved.