Photopolymerizable ormosil films have been deposited using the Aerosol-gel process. Methacryloxypropyl-trimethoxysilane (MTPS) and tetraisopropyl-orthotitanate (TIPT) complexed with methacrylic acid (MAA) were used as sol-gel precursors. Photoinduced processes were sensitized using commercially available photoinitiators. Fourier transform infrared (FTIR) characterization as well as thickness and refractive index measurements have been performed to study photoinduced polymerization and densification mechanisms in ormosil films. Particular attention is paid to the interactive effects of titanium species and photoinitiator on the photoinduced processes. (C) 2004 Elsevier B.V All rights reserved.