Gem-dihydroperoxides as a class of organic peroxides are stable derivatives of ketones and aldehydes. Synthesis of gem-dihydroperoxides are important because these compounds are intermediates in synthesis of some bioorganic active peroxides, such as peroxidic antimalarial drugs [1-3]. In addition, some organic peroxides have been utilized as the radical initiators in chemical industries [4]. Also, recently gem-dihydroperoxides have been used as powerful oxidizing agents in many organic reactions [4]. In this work, chlorosulfonic acid (ClSO3H) has been used as a novel and efficient catalyst for conversion of different aldehydes and ketone (aromatic and aliphatic) to their corresponding gem-dihydroperoxide for the first time (scheme 1). Also, we catalyzed this reaction by tartaric acid as an inexpensive and green catalyst. The reactions have been preceded under mild conditions at room temperature in high yields and good purity. The time of reactions was notable. The structure of obtained products have been confirmed by Fourier transform infrared (FT-IR) and Proton Nuclear Magnetic Resonance (1H NMR) spectroscopy. In addition, amount of peroxide in products have been determined by manganometry and iodometry titration.