The Tl2Se-Sb2Se3 cross section of the Tl-Sb-Se ternary system was studied by both the common thermal analysis (TA) and the X-ray diffraction (XRD). Numerical values of the phase transition temperatures at different alloy compositions within the whole concentration range were obtained. They have been listed in a table that can be used by other authors in any computational treatment of the system. From these data the phase equilibrium diagram has been determined for the title system. The diagram was compared with three different diagrams for the same system published earlier by other authors. As the most important result of the present study, one new chemical compound has been found. (C) 2013 Elsevier B.V. All rights reserved.