In this study, thermodynamic properties of AgSbS2 and Ag3SbS3 have been determined by the advanced EMF method. All the measured phases have been carefully synthetized in evacuated quartz glass ampoules. The synthesized phases were analyzed by the SEM-EDS and DSC techniques. Solid state electrochemical cells of the type (Ag|AgI|Ag-Sb-S-compounds in equilibrium) were applied in EMF measurements. Independent experimental apparatuses were applied to prove the reproducibility of the measured EMF values. The measured E vs. T relations were analyzed, and thermodynamic functions of AgSbS2 and Ag3SbS3 have been determined. Accurate thermodynamic properties of both phases including data in new temperature ranges have been obtained. The results were compared with the available literature data and discussed.