The emerging global demand for energy production has intensified the interest in more effective power generation methods. Thermoelectric materials can be employed to relax global energy problems by converting waste heat into electricity1. Significantly high efficiencies have been obtained in nanostructured lead-based materials, such as (PbTe)m-AgSbTe2 systems. Because of the strict environmental regulations for the use of these systems, new lead-free compounds such as AgSnmSbTe2+m may constitute attractive alternatives. In addition, doping is a potential approach to optimize the thermoelectric properties2. Here, we report new doped-compounds of AgSn2SbSe2Te2 as promising thermoelectric materials. These phases were synthetized by ceramic method at high temperatures. Powder X-ray diffraction (PXRD) patterns were consistent with phases belonging to the Pm-3m space group (Figure 1). Parallelepiped bars for transport measurements were prepared from melted samples or SPS method. AgSn2SbSe2Te2 system exhibited typical degenerate semiconductor behavior, with a carrier concentration of approximately ∼1021 cm-3 . Seebeck coefficient and electrical resistance are +70 μV K-1 and 67.1 mΩ⋅cm at room temperature (R.T), respectively. However, Cu-doped compound shows very low Seebeck coefficients in the temperature range from 50 K (+5 μV K-1) to 250 K (+25 μV K-1). The electrical resistance was almost constant ∼2.5 mΩ⋅cm for Ag0.95Cu0.05Sn2SbSe2Te2 (Figure 1). The carrier concentration is significantly improved by partially substituting Selenium by Iodine: ∼1019 cm-3 for AgSn2SbSe1.98I0.02Te2. The electrical conductivity σ increased with increasing temperature follows Arrhenius-law. Figure 1: PXRD patterns for AgSn2SbSe2Te2 -doped compounds and electrical properties of Ag0.95Cu0.05Sn2SbSe2Te2. Acknowledgements: The authors thank to FONDECYT grant N° 1160685 References 1. Zhang, X. and Zhao, L-D. J. of Materiomics, 2015, 2, 92-105. 2. Han, M.K. et al. Adv. Energy Mater, 2012, 2,157-161.FONDECYTFONDECYT