Ionic liquids have thermophysical and chemical properties that may be suitable for phase change materials (PCMs). Melting points, heats of fusion and heat capacities for a series of imidazolium-based ionic liquids or ethnolamine tetrafluoroborates have been measured by differential scanning calorimeter. The experimental results indicate that long-chain alkylimidazolium bromides are suited for use as PCMs. A quantitative structure-property relationship (QSPR) model for heat of fusion was constructed using six descriptors based on PM3 semi-empirical method. The calculated results gave reasonable correlation and prediction accuracy for 44 kinds of ionic liquids. (C) 2008 Elsevier B.V. All rights reserved.