As-deposited and annealed amorphous SiOxNy/H (0.17 <= x <= 0.96; 0.07 <= y <= 0.27) films were characterized by spectroscopic ellipsometry and room temperature pbotoluminescence measurements. The refractive index of as-deposited silicon oxynitride films could be successfully varied between SiO2 and a-Si with increased silicon content. As-deposited films were annealed under inert conditions at 400-800 degrees C for 4 h. Annealing conditions were insufficient to nucleate silicon nanocrystals in the films. High temperature annealing facilitated the hydrogen diffusion out of the film. This led to the reduced thickness and increased refractive index of the silicon rich oxymnide film. A correlation was seen between the changes in the refractive index, optical band gap, E-04 (energy corresponding to an absorption coefficient of 10(4) cm(-1)) and Urbach Energy as a function of composition and annealing conditions. The influence of annealing conditions on the photoluminescence spectra of silicon rich oxynitride films has been investigated. The room temperature luminescence in annealed SiO0.96N0.27:H films was attributed to the formation of oxygen related defects in these films. In other films, the bonded hydrogen as well as silicon and nitrogen content, played an extremely important role in determining the influence of annealing conditions on the photoluminescence spectra. (C) 2007 Elsevier B.V. All rights reserved.