Form-stable paraffin phase change materials (PCMs), in which the paraffin as a latent heat storage material and the polyolefins as a supporting material, have to be encapsulated because of the paraffin leakage and lipophilicity. A novel microencapsulated PCM in which form-stable paraffin is encapsulated into inorganic silica gel polymer is prepared successfully by in situ polymerization. A differential scanning calorimeter (DSC) is used to measure the thermal properties of the PCM. Moreover, the Washburn equation associated with the wetting properties of powder materials, is used to test the hydrophilic-lipophilic properties of PCM. The results indicate that the optimum microencapsulated PCM is endowed with I good hydrophilicity, and its specific enthalpy maintains 123.78 J g(-1). (c) 2006 Elsevier Ltd. All rights reserved.