Indium sulfide (In2S3) polycrystalline thin films have been deposited on amorphous glass substrates by modulated flux deposition (MFD). The influence of different deposition parameters (elemental sources temperatures, substrate temperature, substrate angular velocity) has been studied. Structural and optical characterization has been carried out by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and optical and profilometric measurements. All the samples had a tetragonal structure (beta-In2S3) with high (103) preferential orientation. Optimized samples showed good coverage and a small-grain homogeneous microstructure. A direct optical transition was observed, with a bandgap energy (E-g) of 2.75 eV for 100-nm-thick films. (c) 2005 Elsevier B.V All rights reserved.