Title Thermodynamic study of the ternary system: KBr+ Mannitol+ H2O by Potentiometric Method Type of Research Presentation Keywords Activity Coefficients, Gibss free energy of transfer, Solvation, KBr and Mannitol. Abstract This research purposes on the thermodynamics modeling of the ternary KBr+Mannitol+ water at 298.15 K by electromotive force ( emf ) measurements. Electrochemical cells with a potassium ion selective electrode (K–ISE) versus a bromide ion selective electrode (Br–ISE) as a reference electrode were used to determine the activity coefficients for KBr– monosaccharide (Mannitol) systems in water at 298.15 K. Pitzer ion-interaction model has been used for correlating the data. A comparison of the results with references shown that agreement is excellent. The Gibbs free energy of transfer from water to mix solvent for KBr were evaluated together with the model parameter. Researchers Mahsa Ghasemi Ilkhechi (First Researcher)، Rahman Salamat Ahangari (Second Researcher)