In2S3 films of different thicknesses were deposited onto Corning 7059 glass substrates using close spaced evaporation method, at a constant substrate temperature and growth rate of 300 degrees C and 30 angstrom/s, respectively. The deposited layers were then annealed in vacuum at temperatures (T-a) in the range 100-500 degrees C for 1 h and changes in the chemical and physical properties of the layers were investigated. The films annealed at T-a < 300 degrees C resulted in films that consisted of both cubic and tetragonal phases, while for films annealed at T-a >= 300 degrees C only the tetragonal beta-In2S3 phase was found to be present. A considerable change in morphology was observed for the film thickness of > 300 nm and annealing temperature of 300 degrees C. A highest optical transmittance was found to be 92% in the annealing temperature range, 300 degrees C < T-a <400 degrees C with a nominal reduction in the energy band gap. The electrical resistivity of the layers was found to decrease with increase of annealing temperature up to 400 degrees C. The observed changes in the physical properties in relation to the annealing temperature for the films of different thicknesses were reported and discussed. (C) 2010 Elsevier B.V. All rights reserved.