The preparation of Co(II) supported magnetic heterogeneous catalyst, i.e. Fe3O4@SiO2–NH2@CS–Co, and its efficient and selective catalytic properties toward the oxidation of ethylbenzene to acetophenone are presented. The materials were characterized by various physicochemical techniques such as scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, vibrating sample magnetometer, elemental analysis, inductively coupled plasma-atomic emission spectrometer and X-ray photoelectron spectroscopy, etc. The reaction conditions were thoroughly investigated and highly improved catalytic performance (82.5% conversion of ethylbenzene and 80.1% selectivity to acetophenone) was gained under more mild reaction conditions of lower temperature (70 °C), shorter reaction period (60 min) and cheaper and greener oxygen source (H2O2). More importantly, it could be reused successively at least 10 times when more than 80% of its catalytic activity maintained.