Abstract This work presents experimental investigation of the thermoelectric and structural characteristics of new double half Heusler alloys Hf_2-xTi_xFeNiSb₂ (x= 0, 0.15, 0.25 and 0.4). The studied samples were synthesized using different techniques of melt spinning, arc melting and spark plasma sintering. Crystal structure of the studied compounds was examined via x-ray diffraction (XRD). A face centered cubic structure was found to be the dominant crystallization phase. Homogeneity and relatively high density were obtained in the fabricated samples. Thermoelectric properties of the samples were studied over a temperature range from 300 to 800 K. Thermal conductivity was found to be significantly decreased with the Titanium (Ti) doping due to enhanced the phonon scattering. The highest value of the thermoelectric figure of merit was obtained for Hf_1.75Ti_0.25FeNiSb₂ to be 0.28±0.014 at 800 K.