The electrochemical study on the Tl2Se-Ag2Se solid system was performed using emf measurement of concentration cells to verify the phase equilibrium diagram for the system published earlier by other authors. Partial molar thermodynamic functions of thallium at 443 K were determined for the ternary chemical compounds formed in this system. The study resulted in significant correction of the former diagram. The most important is that two new chemical compounds have been found in the present work instead of two another ones reported earlier. (C) 2017 Elsevier Ltd. All rights reserved.