A thermodynamic study of the solid two-phase regions of the binary Ag-Te system was made by an improved EMF method, using fast ion conductor RbAg4I5 as the solid electrolyte. The EMF measurements were made on three galvanic cells: [Ag RbAg4I5 Ag5Te3 + Te], [Ag RbAg4I5 Ag5Te3 + Ag1.9Te] and [Ag RbAg4I5 Ag1.9Te + Ag2Te]. Based on the results obtained, the EMF for each equilibrium phase assembly was expressed as a function of temperature, in the different regions of thermal stability of the substances. By using the observed EMF and temperature relations, the thermodynamic functions of the stoichiometric equilibrium phase assemblages: Ag5Te3-Te, Ag5Te3-Ag1.9Te, Ag5Te3-Ag2Te and Ag2Te-Ag1.9Te, in the lowerature range 22-204°C, as well as phase transformation temperatures, have been determined. Agreement between the results obtained and the literature values were established.