Adsorption and reaction of acetic acid on a CeO2(1 1 1) surface was studied by a combination of ultra-high vacuum based methods including temperature desorption spectroscopy (TPD), soft X-ray photoelectron spectroscopy (sXPS), near edge X-ray absorption spectroscopy (NEXAFS) and reflection absorption IR spectroscopy (RAIRS), together with density functional theory (DFT) calculations. TPD shows that the desorption products are strongly dependent upon the initial oxidation state of the CeO2 surface, including selectivity between acetone and acetaldehyde products. The combination of sXPS and NEXAFS demonstrate that acetate forms upon adsorption at low temperature and is stable to above 500 K, above which point ketene, acetone and acetic acid desorb. DFT and RAIRS show that below 500 K, bridge bonded acetate coexists with a moiety formed by adsorption of an acetate at an oxygen vacancy, formed by water desorption. (C) 2015 Elsevier B.V. All rights reserved.