A facile route based on ultrasound-assisted sol gel method has been developed and applied to rapid synthesis of polyethylene glycol (PEG)/silicon dioxide (SiO2) composite form-stable phase change materials (PCMs) without co-solvent and surfactant. This method was carried out under ultrasonic power of 300 W using HCl and Na2CO3 as the acidic and alkaline catalyst, respectively. The temperature is below 50 degrees C. The PCMs were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC) and thermogravimetric analysis apparatus (TGA) measurements. The PCMs display low density, high volume energy density, excellent form-stable effect, good phase-change and temperature control performance, which are very important for the actual application of PCMs in energy-saving construction materials. (C) 2013 Elsevier Ltd. All rights reserved.