We report the synthesis, characterization and thermoelectric properties of lead-free AgSnmSbSe2Tem (m = 2 and 10) systems. Powder X-ray diffraction patterns and Rietveld refinement results were consistent with phases belonging to the Pm (3) over barm space group. The microstructures and morphologies of these systems were investigated using scanning electron microcopy (SEM) and high-resolution transmission electron microscopy (HRTEM). Parallelepiped bars for transport measurements were prepared using two methods: the classical method (CM) from melted samples and the spark plasma sintering (SPS). The AgSnmSbSe2Tem (m = 2 and 10) systems exhibited typical degenerate semiconductor behavior, with a carrier concentration of approximately +10(21) cm(-3). We determined that the Seebeck coefficient can be substantially increased from approximately +40 V K-1 (CM) to +70 mu V K-1 (SPS) in AgSn2SbSe2Te2 at room temperature. Consequently, the power factor (S(2)cr) was similar to 22 W cm(-1) K-2. On the basis of the electrical and thermal transport properties, ZT values of similar to 0.10 were obtained at room temperature. (C) 2018 Elsevier B.V. All rights reserved.