A segment - based molecular thermodynamic model is developed to calculate the Gibbs energy of nonionic surfactant solutions. The critical micellar concentrations of five single aqueous surfactant systems at different temperatures are correlated. The critical micellar concentrations of fourteen single aqueous surfactant systems at different temperatures are predicted by using the adjustable parameters. The predicted values are satisfactory. Compared with the Chen-NRTL model

this model has better accuracy and good prediction function.