ZnO nanoparticles with average diameter of 25 nm were synthesized by a modified sol-gel method and used in the preparation of (in wt.%) (100-x) poly(vinyl alcohol) (PVA)/x ZnO nanocomposite films, with x = 0, 1, 2,3, 4, and 5. The PVA/ZnO films were exposed to UV radiation for 96 h and their thermal, morphological, and spectroscopic properties were investigated. In inert atmosphere, the nanocomposite films showed lower thermal stability than the pure PVA film, and the calorimetric data suggest an interaction between PVA and ZnO in the nanocomposite films. Some crystalline phases could be seen in the films with ZnO, and a direct dependence on the ZnO concentration was also observed. The original structure of ZnO nanoparticles remained unaltered in the PVA matrix and they were uniformly distributed on the film surface. The roughness of the PVA film was not modified by the addition of ZnO; however, it increased after 96 h of UV irradiation, more significantly in the nanocomposite films. The films showed an absorption band centered at 370 nm and a broad emission band in the UV-vis region when excited at 325 nm. (C) 2011 Elsevier B.V. All rights reserved.