A heterogeneous catalyst based on Cobalt as active sites and amine functionalized magnetic mesoporous silica nanospheres as support was successfully prepared by the complexation of Cobalt(II) acetylacetonate [Co(acac)(2)] with (3-aminopropyl)triethoxysilane (3-APTES) functionalized magnetic nanoparticles. The catalyst was characterized by transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), N-2 adsorption-desorption and a vibrating sample magnetometer (VSM). The obtained catalyst exhibited excellent activity and selectivity for epoxidation of olefins by using molecular oxygen as an oxidant, especially for the epoxidation of a-methylstyrene (conversion: up to 98%; selectivity: exceed 98%). Meanwhile, the novel catalyst could be recovered by magnetic separation from the reaction mixture and recycled five times without any significant loss in activity. (C) 2015 Elsevier B.V. All rights reserved.