Abstract. Ag8Ge1-xMnxTe6 solid solutions with different manganese content (x = 0; 0.05; 0.1; 0.2) were prepared by alloying and further pressing the powders under a pressure of 0.6 GPa. By the X-ray diffraction studies have shown that the introduction of manganese atoms leads to the compressibility of the Ag8Ge1-xMnxTe6 lattice. All p-type samples had high resistance below the transition at temperatures of 180 - 220 K. An increase in electrical conductivity in the range of 220 - 300 K was analyzed using the Mott ratio; at temperatures T > 320 K, semiconductor behavior is observed in all compositions. The highest thermoelectric figure of merit ZT = 0.7 at 550 K was obtained for a solid solution of the composition Ag8Ge1-xMnxTe6 (х = 0.05).