Abstract Si–Ge solid solutions are known to be good high-temperature thermoelectric materials. The aim of the paper is to study the thermoelectric properties of Si–Ge ( x =0.01–0.11) whiskers in temperature range 4.2–500 K. Measurements were carried out on whiskers with a boron concentration in the vicinity to metal–insulator transition from dielectric side of the transition. Temperature dependencies of Seebeck coefficient for whiskers with various resistivity ( ρ =0.01–0.05 Ω cm) have been investigated. It was found that Seebeck coefficient as a rule decreases slowly at temperature growth. A slope of α ( T ) curves depends on whisker doping level. The α -value is about 1 mV/K, which is prospective for whisker applications in temperature sensors. To estimate an efficiency of such sensor we have calculated figure of merit Z for the whiskers. Depending on doping level the whisker figure of merit is ∼(1–2)×10 −4 K −1 in the investigated temperature range. Therefore, the obtained results allow to conclude that heavily doped Si–Ge ( x =0.01–0.1) whiskers can be successfully used for design of sensors for measuring of cryogenic and the above room temperatures.