Indium oxide (In2O3) thin films were prepared by flash evaporated technique under various substrate temperatures in the range of 303-673 K and systematically studied the structural, electrical and optical properties of the deposited films. The films formed at substrate temperatures of < 373 K were amorphous while those deposited at higher substrate temperatures (≥ 373 K) were polycrystalline in nature. The optical band gap of the films decreased from 3.71 eV to 2.86 eV with the increase of substrate temperature from 303 K to 673 K. Figure of merit of the films increased from 2.8 × 103 Ω- 1 cm- 1 to 4.2 × 103 Ω- 1 cm- 1 with increasing substrate temperature from 303 K to 573 K, thereafter decreased to 2.2 × 103 Ω- 1 cm- 1 at higher temperature of 673 K. © 2007 Elsevier B.V. All rights reserved.