Abstract: According to Bagleys definition of solubility parameter, an expression is established which could be used to calculate solubility parameter of liquids at various temperature where ρm is molar density of liquid. A and B are two correlative characteristic constants. For the general small molecule liquids both A and B are functions of molecular size only. A method of group contributions is developed to determine accurately characteristic constant A of various liquids from their structural formulae. The predicted solubility parameters showed an average relative deviation from the experimental values of about ±0.8% tor sixty liquids.