Abstract: A new viscosity model is presented according to the theory of rate processes and solute aggregation for aqueous nonelectrolyte solutions. Each of the adjustable parameters estimated from the viscosity of binary systems has its definite physical meaning. It is found that the ordering in aqueous solution have a larger effect on the excess free energy of activation of viscous flow than heat of mixing. There are two different proportionality constants between excess enthalpy and excess enthalpy of activation of viscous flow, and between excess entropy and excess entropy of activation of viscous flow. The correlation deviation for binary system is generally less than 1%. The prediction of viscosity for ternary aqueous solutions is satis- factory with the use of the binary parameters, the deviation is less than 5%.