Furthermore the thermoelectric behavior of Ti1−xHfxNiSn and respective Sn/Sb substituted compounds in the temperature range from room temperature to 873 K was characterized by measurements of the electrical resistivity, ρ, the Seebeck coefficient, S, the thermal conductivity, λ, from which we calculated the dimensionless figure of merit, ZT, and also the efficiency, η, for thermoelectric power generation. Due to the high market price of Hf, a Ti1−xZrxNiSn series with and without Sn/Sb substitution was successfully synthesized with ZT∼1 for TiNiSn and ZrNiSn and ZT∼1.2 for Ti0.5Zr0.5NiSn0.98Sb0.02. The experimental data are discussed in the context of respective DFT calculations.