Abstract: Combining the analytic equation for molecular radial distribution function proposed in paper( I ) with Flory-Huggins equation, the molecularthermodynamic model for a non-electrolyte solution is established and is applied to the complicated metal solvent extraction systems, in which Co or Cu as well as Co and Cu are extracted by DEHPA. The activity coefficients for all components in the above systems and the thermodynamic equilibrium constants tor the extraction reactions are predicted by the model with the help of the experimental data from three binary systems. The predicted results are in good agreement with the experimental data.