Abstract This paper presents the structural, electrical and optical properties of indium oxide thin films deposited by (1) pyrosol technique in comparison with the results that were obtained by spraying the same solution using (2) a pneumatic spray system. Films were deposited at temperatures ranged between 623 and 863 K onto glass substrates and investigated by scanning electron microscopy and X-ray diffraction. The transmission and reflectance spectra were determined in the 260–2600 nm spectral range. Resistivity as low as 6×10 −3 Ω cm with high optical transmission (>90%) have been obtained in In 2O 3 thin films deposited, when the ultrasonic atomizer system was used. The figures of merit Φ TC= T 10/ R sh of films deposited using the two methods were calculated at different wavelengths. The advantages of the pyrosol method were obvious. The atomization of solution using the ultrasonic system leads to an improvement of the structural and electrical properties of films and allows the deposition of films with high transparency and electrical conductivity at lower substrate temperatures (∼673 K) compared to that needed in the case of pneumatic spray method (⩾773 K).