Ionic liquids (ILs) are a type of potential green solvents, which can be used as a media for reaction and separation. The infinite-dilution activity coefficient is an important parameter to measure the interaction between ILs and solutes. In this work, we proposed a new method to predict infinite-dilution activity coefficients of ILs at different temperatures. A temperature-dependent quantitative structure-property relationship (QSPR) model was developed for a series of organic solutes in the ionic liquid trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide. By using genetic algorithm-variables subset selection (GA-VSS) and ordinary least-square regression (OLS) methods, six variables, including temperature and five significant molecular descriptors, were selected and used to build the temperature-dependent prediction model. The satisfactory results of the internal and external validations proved the reliability, stability and predictive ability of the built model. (C) 2010 Elsevier B.V. All rights reserved.