Cu(II)–Schiff base complex-functionalized magnetic Fe3O4 nanoparticles were prepared and characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy techniques. This compound acts as a highly active and selective catalyst for the oxidation of sulfides and thiols. These reactions can be carried out in ethanol or solvent-free conditions in the presence of hydrogen peroxide with complete selectivity and very high conversion under mild reaction conditions. The designed catalytic system prevents effectively the over-oxidation of sulfides to sulfones. Separation and recycling can also be easily done using a simple magnetic separation process