Molybdenum (VI) complex, namely molybdenum dioxobis(2,4-pentanedione) [MoO2(acac)(2)] used as epoxidation catalyst species, was synthesized and characterized by elemental analysis and infrared spectrum. Polystyrene-supported molybdenum dioxobis(2,4-pentanedione) [MoO2(acac)(2)] for synthesis of epoxycyclohexane was prepared by phase transfer catalysis method. Effects of various factors in synthesis of epoxycyclohexane by reaction of cyclohexene and t-BuOOH in the atmosphere of nitrogen catalyzed by polystyrene-supported MoO2(acac)(2) were also investigated. Under the following conditions, n(cyclohexene):n(t-BuOOH)=3.5:1 (based on 0.1 mol of t-BuOOH), volume of solvent similar to10 ml, reaction temperature similar to80degreesC, reaction time similar to60 min, and mass of molybdenum in the catalyst similar to2.30 x 10(-3)g, the yield of epoxycyclohexane on the basis of t-BuOOH is over 99.5%, and the purity of epoxycyclohexane is about 99.9% by gas chromatogram(GC) analysis.