Effect of Fe doping on the structure, optical and thermoelectric properties of SrTi 0.8 Sn 0.2 O 3 sample has been investigated. The SrTi 0.8−x Sn 0.2 Fe x O 3 (x = 0, 0.1, 0.3) samples are fabricated using solid-state synthesis route. It is observed that Fe doping helps in reducing the densification temperature of SrTi 0.8 Sn 0.2 O 3 during spark plasma sintering. Precipitation of Sn has been observed in SrTi 0.8−x Sn 0.2 Fe x O 3 (x = 0, 0.1) samples while the SrTi 0.8−x Sn 0.2 Fe x O 3 (x = 0.3) sample is of purely single cubic perovskite phase. All the samples consist of nanocrystalline grains and the grain size varies between 150 to 200 nm. Fourier transform infrared spectroscopy (FTIR) analysis reveals the distortion of TiO 6 octahedra due to the increase in Fe content. Raman spectroscopy analysis has shown that perovskite cubic structure is stable from room temperature to 873 K. From thermophysical measurements, it is shown that the Fermi band gap reduces from 2.87 to 0.66 eV with increase in Fe in the investigated samples. The Seebeck co-efficient is found to change the sign from n–type to p-type with the increase of Fe concentration in SrTi 0.8 Sn 0.2 O 3 which is an interesting observation to obtain p-type SrTiO 3 based thermoelectric materials. The optical and thermoelectric properties show that Fe doping improves the thermoelectric properties of SrTi 0.8 Sn 0.2 O 3 ceramics by altering the Seebeck coefficient and thermal conductivity. © 2019 IOP Publishing Ltd.