Catalytic epoxidation of alkenes with iodobenzene diacetate by the manganeseporphyrin in environmentally benign and ambient temperature ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6) has been studied. The use of [binim]PF6 as the reaction medium brought definitive advantages over an organic catalytic phase: the reaction proceeded with high efficiency and the rate was much higher than that of in CH2Cl2; the ionic liquid-manganeseporphyrin system could be reused at least 12 times without losing activity. The mechanism of the reaction was also investigated. (C) 2003 Elsevier B.V. All rights reserved.