X-ray phosphor films based on composite materials, for conversion of x rays into visible light, have been synthesized for large area imaging applications. Here the major components are gadolinium oxysulfide doped with terbium (Gd2O2S:Tb), polyvinyl alcohol and water. A small amount of additives (ethylene glycol and sulfonated type agents) were incorporated to disintegrate aggregated phosphor powders and to minimize coating defects. The films, with thicknesses ranging from 380 to 1100 mu m and phosphor grain size of 10 mu m, were deposited onto glass substrates. The coating quality of the films was evaluated via confocal laser beam scanning microscopy. The x-ray absorption efficiency and the green light emission intensity of the films were measured as functions of film thickness and x-ray source voltage.