Indium chloride doped zinc oxide (ZnO:In) thin films were deposited onto glass substrates using zinc acetate by Ultrasonic Spray Pyrolysis technique. The effect of substrate temperature, deposition time and acetic acid added to the spraying solution on the structural, electrical and optical properties of these ZnO:In films is reported. The films were in all cases polycrystalline with a hexagonal (wurtzite) structure, a transparency over 80% and resistivity of the order of 10(-3)-10(-2)Omega.cm. The resistivity was dependent on the volume % of acetic acid added to the spraying solution. The minimum resistivity value was obtained with a 5 vol.% acetic acid (pH=3.71) at substrate temperature of 450 degrees C. The deposition rates obtained were as high as 180 angstrom.min(-1) at a substrate temperature of 450 degrees C. (C) 2012 Elsevier B. V. All rights reserved.