Effects of olefin on adsorptive deep desulfurization of gasoline over Ce(IV)Y zeolites have been studied via a FT-IR spectrometry and a fixed-bed adsorption technique at room temperature and atmosphere pressure by using model fuels containing thiophene and I-octene as model compounds. The adsorptive selectivity for thiophene decreases significantly as the concentration of I-octene increases. The difference in the FT-IR spectra between the Ce(IV)Y zeolite samples adsorbing the model fuels with and without 1-octene can be attributed. to the stronger adsorption interactions of 1-octene with the Ce(IV)Y zeolite than those for thiophene. For minor content (500 mu g/g) of thiophene and 1-octene, the FT-IR spectra show that the Ce(IV)Y zeolites have the preference to adsorb thiophene rather than 1-octene. However with the content of 1-octene increasing in the model fuel up to 150 mg/g, 1-octene can be adsorbed on the Ce(IV)Y zeolites remarkably, resulting in a descending adsorptive selectivity of the Ce(IV)Y for removing thiophene from the model fuel. (C) 2009 Elsevier B.V. All rights reserved.