A quantitative structure-property relationship (QSPR) study is carried out to develop correlations that relate the structures of organic compounds to their infinite dilution activity coefficients, gamma(infinity), in water at 298.15 K, and three correlations were proposed for hydrocarbons, oxygen containing organic compounds and halogenated hydrocarbons, respectively. Since the molecular descriptors can be calculated easily, the correlations are simple in application with C Good accuracy, which provide an easy, direct and relatively accurate way to calculate gamma(infinity) in aqueous solutions.