Anewreaction-controlledphase-transfercatalystsystem,lacunaryKegginpolyoxotungstate[C7H7N(CH3)3]9PW9O34hasbeensynthesizedandusedforcatalyticepoxidationofolefinswithH2O2astheoxidant.Infraredspectrawereusedtoanalyzethebehaviorofthephasetransferofcatalyst.Inthissystem,thecatalystnotonlycanactashomogeneouscatalystbutalsoasheterogeneouscatalysttobeeasilyfilteredandreused.Theepoxidarionreactioniscleanandexhibitshighconversionandselectivityaswellasexcellentcatalyststability.