Two new nanohybrid compounds as heterogenous catalyst were prepared by reaction of Lacunary Keggin-type polyoxometalate compounds ([SiW11O39](8-) and [PW11O39](7-)), molybdenyl acetylacetonate [MoO2(acac)(2)] and ethylenediamine (en), (1 and 2 respectively) species and characterized by elemental analysis and various routine techniques. The catalytic activities of these nanocatalysts examined for the epoxidation of linear, cyclic and phenyl-substituted olefins using tert-Butyl hydroperoxide (tert-BuOOH) as oxidants. The synergistic effect between molybdenyl acetylacetonate complex and lacunary Keggin-type polyoxometalate plays an important role in the promotion of catalytic activity. The catalysts were recovered and reused at least six times without obvious losing of activity and the yields for catalyst recovery are all above 91%. [GRAPHICS] .