Abstract— <p>A promising method for increasing the efficiency of thermoelectric energy converters as alternative energy sources is nanostructuring of thermoelectric materials used to manufacture thermoelements. The widespread use of thermoelectric devices is hampered by their low efficiency, which is determined by the thermoelectric figure of merit <i>ZT</i> of thermoelectric materials. The paper investigates the stability of the properties of low-temperature nanostructured thermoelectric materials based on solid solutions of Bi₂Te_2.8Se_0.2 (0.16 wt % CdCl₂) of the <i>n</i>-type and Bi_0.5Sb_1.5Te₃ (2.2 wt % Te and 0.16 wt % TeI₄) of the <i>p</i>-type obtained as a result of grinding in a planetary ball mill and subsequent compaction by spark plasma sintering. Thermoelectric materials Bi₂Te_2.8Se_0.2 and Bi_0.5Sb_1.5Te₃ have high maximum values of thermoelectric figure of merit <i>ZT</i>, equal to 1.17 and 1.23, respectively. Thermal stability of the properties of Bi₂Te_2.8Se_0.2 and Bi_0.5Sb_1.5Te₃ materials was investigated using multiple measurements using differential scanning calorimetry and thermogravimetry. Thermoelectric and electrophysical characteristics of thermoelectric materials were obtained at temperatures up to 500 K. It was established that nanostructuring does not have a significant effect on the thermal stability of the studied low-temperature nanostructured thermoelectric materials.</p>