We report on thin-film transistors based on Ga2O3 films grown by ultrasonic spray pyrolysis in ambient atmosphere at 400–450 °C. The elemental, electronic, optical, morphological, structural, and electrical properties of the films and devices were investigated using a range of complementary characterisation techniques, whilst the effects of post deposition annealing at higher temperature (700 °C) were also investigated. Both as-grown and post-deposition annealed Ga2O3 films are found to be slightly oxygen deficient, exceptionally smooth and exhibit a wide energy bandgap of ∼4.9 eV. Transistors based on as-deposited Ga2O3 films show n-type conductivity with the maximum electron mobility of ∼2 cm2/V s.