High performance liquid chromatography of aldohexoses, the corresponding 6-deoxy derivatives, and several malto-oligosaccharides has been examined with a Hitachi ^#3013-N column, and with aqueous CH₃CN eluents, at various temperatures. It has been shown that when the concentration of CH₃CN in the eluent is higher than 30%, the system works as a partition chromatography, whereas with pure phosphate buffer eluent (H₂O) it works as a gel filtration column. Some of the values of the free energy ΔG°and enthalpy ΔH°, assignable to the glucose residue and the 6-OH group in some particular states have been estimated. A possible use of such thermodynamic functions in medicinal chemistry is suggested.