A series of polyimide/zirconia (PI/ZrO2) hybrid films were synthesized based on zirconium n-butoxide, pyromellitic acid dianhydride (PMDA) and 4,4'-oxydianiline (ODA) by a sol-gel process. The atomic oxygen (AO) exposure tests were carried out using a ground-based atomic oxygen effects simulation facility. The effects of ZrO2 content on the morphology and structure evolvement of PI/ZrO2 hybrid films were investigated using field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectrometer (XPS), respectively. The results indicated that a zirconia-rich layer was formed on the polyimide film sourcing from the zirconium n-butoxide after AO exposure, which decreased the erosion rate and obviously improved the AO resistance of polyimide films. (C) 2010 Elsevier B.V. All rights reserved.