Thermoelectric (Peltier) heat pumps are capable of refrigerating solid or fluid objects, and unlike conventional vapor compressor systems, they can be miniaturized without loss of efficiency. More efficient thermoelectric materials need to be identified, especially for low-temperature applications in electronics and devices. The material CsBi₄Te₆ has been synthesized and its properties have been studied. When doped appropriately, it exhibits a high thermoelectric figure of merit below room temperature (ZT_max ∼0.8 at 225 kelvin). At cryogenic temperatures, the thermoelectric properties of CsBi₄Te₆ appear to match or exceed those of Bi_{2– x}Sb_xTe_{3– y}Se_yalloys.