By e.m.f. measurements of the relatively to concentrated chains thallium electrode the solid-phase equilibria and thermodynamic properties of the system Tl–Bi–Te in the concentration area Tl₂Te–Bi₂Te₃–Te have been investigated. The boundaries of the section of phase areas on T–x–y phase diagram, were clarified, the partial thermodynamic functions of thallium in alloys and standard thermodynamic functions of formation of phases along sections Tl₂Te–Bi₂Te₃ and Tl₅Te₃–Tl₉BiTe₆ were calculated.