Abstract Polysiloxane/POSS hybrid coatings were deposited on Kapton substrate by copolymerizing epoxy-modified polysiloxane resin with trisilanolphenyl-silsesquioxane (POSS) and their atomic oxygen (AO) erosion resistance was tested in a ground-based AO simulator. The surface morphologies and structures of the exposed and unexposed hybird coatings were analyzed by scanning electronic microscopy and X-ray photoelectron spectroscopy. The results indicate that the polysiloxane/POSS hybrid films are capable of providing protection against AO attack. Unlike the polysiloxane coating, no crack was observed in the hybird coatings during AO exposure. The results of XPS analysis indicated that a continuous high-quality protective SiO2 surface layer was formed on on the polysiloxane/POSS hybrid coatings after the AO exposure. It can prevent further degradation of the underlying polymer with increased exposure to the AO flux and provide high-quality erosion protection for these materials. The erosion yield of the polysiloxane/POSS hybrid coatings decreased by a factor of more than two orders of magnitude compared with that of the polyimide film, reduced to 0.4% of Kapton film.