The invention relates to the use of a thermoelectric material for thermoelectric purposes at a temperature of 150 K or less, said thermoelectric material is a material corresponding to the stoichiometric formula FeSb2, wherein all or part of the Fe atoms optionally being substituted by one or more elements selected from the group comprising: Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, La, Hf, Ta, W, Re, Os, Tr, Pt, Au, Hg, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and a vacancy; and wherein all or part of the Sb atoms optionally being substituted by one or more elements selected from the group comprising: P, As, Bi, S, Se, Te, B, Al, Ga, In, Tl, C, Si, Ge, Sn, Pb and a vacancy; with the proviso that neither one of the elements Fe and Sb in the formula FeSb2 is fully substituted with a vacancy, characterised in that said thermoelectric material exhibits a
power factor (S2σ) of 25 μW / cmK2 or more at a temperature of 150 K or less. The invention also relates to
thermoelectric materials per se falling within the above definition.