Optically transparent Al2O3 films has been synthesized, on quartz substrates at 500, 600 and 700 degrees C, from 0.02 M aluminum acetyl acetonate (Al(acac)(3)) in ethanol, by using ultrasonic spray pyrolysis technique. The films synthesized at 500, 600 and 700 degrees C are amorphous having average particle sizes 27 +/- 6, 18 +/- 3 and 14 +/- 3, respectively. The films are found to be 95% optically transparent in the visible region. The optical transparency of the films in the ultraviolet region is found to increase with increase in deposition temperature. The observed increase in optical band gap and decrease in refractive index is attributed to the decrease in particle size with increase in deposition temperature. The stoichiometry and chemical bonding of the amorphous film studied using XPS and FTIR spectroscopy revealed the presence chemisorbed oxygen. (C) 2011 Elsevier B.V. All rights reserved.