The SnTe–Sb2Te3 system was investigated by using EMF measurements of reversible concentration cells relative to the SnTe electrode in the 300–400 K temperature range. The formation of solid solutions (up to 20 mol%) based on Sb2Te3 was confirmed. Based on EMF measurements, the equations of the temperature dependences of the EMF for solid solutions based on Sb2Te3 with compositions of 5, 10, and 20 mol% SnTe were obtained and these results were furtherly used to calculate the partial thermodynamic functions of SnTe in alloys. The standard thermodynamic functions of the formation of solid solutions of the above compositions were calculated by graphical integration of the Gibbs-Duhem equation along the SnTe–Sb2Te3 section