Abstract: The primary thermodynamic dissociation constants of glycine were studied by means of EMF measurements of the cell without liquid junction at different temperatures from 278.15 to 318.15 K in the 0.2 mass fraction of ethanolwater mixed solvent. 　　The first dissociation constants of glycine were calculated by using the polynomial approach proposed on the basis of Pitzer′s electrolytic solution theory and traditional extrapolation on the basis of extended DebyeHückel equation.The results show that both methods are in agreement with each other.The thermodynamic quantities of the first dissociation process of glycine in the mixed solvent were calculated and the results were discussed.

Key words: Thermodynamic, EMF, Dissociation constant, Glycine