A non-liquid-junction electrochemical cell composed of a potassium ion selective electrode(K-ISE) against a chloride ion selective electrode (Cl-ISE) as a reference electrode was employed to study the thermodynamic parameters of weak interactions between aqueous cesium chloride and the monosaccharides (D-glucose, D-galactose, D-xylose, and D-arabinose) at T = 298.15 K. Activity coefficients for this system obtained from electromotive force measurements indicate that they have a close relationship with the stereostructure of the saccharide. The Gibbs free energy pair interaction parameters and salting constants were also evaluated; these can characterize the interaction between the saccharides and CsCl in water. The results were interpreted on the basis of a model of structural and electrostatic interaction and the hydration effect of the hydroxyl ion of these saccharides.