Alkyl aryl sulfides were enantioselectively oxidized in the crystalline cyclodextrin (CD) complexes under various conditions. The oxidation of alkyl phenyl sulfoxides in the β-cyclodextrin (β-CD) complexes resulted in higher chiral induction than that in the α-CD complexes. Methyl 1- or 2-naphthyl sulfides were oxidized more enangroup, the reaction of the γ-CD complex increased the chiral induction reversely. The highest optical yield, 81%, was achieved in the combination of peracetic acid and methyl 1-naphthyl sulfide in the crystalline β-CD complex suspended in water at the oxidizing condition of 0°C under nitrogen, which afforded the formation of the (S)-(-)-sulfoxide in high chemical yield without formation of sulfone. The binding constants, K (M −1 ), were not reflected on the chiral induction for the oxidation with the crystalline CD complexes