ZnO ultrafine particle (UFP) films were deposited on glass andSiO2substrates by a direct current gas discharge activated reactive evaporation method. The effect of substrate temperature and annealing on the structure and morphology of ZnO UFP films was studied by x-ray diffraction and scanning electron microscope. The results show that the spherical island density decreases with increasing annealing temperature and the structure becomes polycrystalline with a (002) preferential orientation as the substrate temperature increases. In addition, angle resolved x-ray photoelectron spectroscopy was used to study the absorption of water on the ZnO UFP film surface by measuring the two deconvoluted peaks for O1s.The two deconvoluted peaks for O1swere located at 533.2 and 534.8 eV. The absorption coefficients of water on the surface were 0.52 and 0.43, respectively, for nonannealed and annealed ZnO UFP films.