Ozone (O₃) adsorption on CeO₂ pretreated under different conditions and characterized by low-temperature CO adsorption was studied by Fourier transform infrared (FTIR) spectroscopy at 77-300 K. Preliminary exposure to CO₂, pyridine, acetonitrile, or methanol at 293 K or to CO at 77 K, as well as adsorption of ¹⁸O substituted O₃ were used to clarify the nature of adsorption sites and the structure of the surface species. In O₃ molecule is no longer symmetric but is bound to a surface Ce⁴⁺ ion via one of its terminal oxygen atoms. Basic surface sites of the samples pretreated at 773 K account for O₃ decomposition, which occurs almost explosively at 77 K but could be inhibited if O₃ adsorption is performed from the solution in liquid oxygen. Formation of ozonide O₃^- (bands at 792 and 772 cm^-1) and superoxide O₂^- (band at 1128 cm^-1) species was detected; these species are believed to be the intermediates of O₃ decomposition on basic sites. On ceria, O₃ does not react at 77 K with adsorbed CO, but ozonolysis of surface methoxy groups proceeds slowly, leading to a formate surface species.