Nanoparticles have recently emerged as efficient alternatives for the immobilization of homogeneous catalysts. However, particles with diameters of less than 100 nm are difficult to separate by filtration techniques; this draw back can be overcome by using magnetic nanoparticles, which can be easy recovered by external magnet [1]. Sulfoxides are fine chemicals, pharmaceuticals and valuable intermediates in the synthesis of chemically useful and biologically active molecules [2]. Oxidation of sulfides is the most straight forward method for the synthesis of sulfoxides. Concerning the green oxidant, hydrogen peroxide is one ofthe most powerful candidates besides molecular oxygen, becauseit is inexpensive, readily availableand high atom efficiency. In continuation of our studies [3], herein, we report the magnetic nanoparticle supported sulfuric acid (MNPsSSA) as a novel and reusable nanocatalyst for the oxidation of sulfides to sulfoxides using H2O2 in water at room temperature (Scheme 1). The MNPsSSA was prepared by the concise route This method offers several advantages including high yield, short reaction time, simple work up procedure, ease of separation, and recyclability of the magnetic nanocatalystwithout significant loss of their catalytic efficiency.