Cysteine-persulfide (Cys-SSH) is a cysteine whose sulfhydryl group is covalently bound to sulfur (sulfane sulfur). Cys-SSH and its glutathione (GSH) counterpart (GSSH) have been recognized as redox regulators, some of which were previously ascribed to cysteine and GSH. However, the production of Cys-SSH and GSSH is not well understood. Here, we show that 3-mercaptopyruvate sulfurtransferase (3MST) produces Cys-SSH and GSSH together with the potential signaling molecules hydrogen per- and tri-sulfide (H2S2 and H2S3). Cys-SSH and GSSH are produced in the brain of wild-type mice but not in those of 3MST-KO mice. The levels of total persulfurated species in the brain of 3MST-KO mice are less than 50% of that in the brain of wild-type mice. Purified recombinant 3MST and lysates of COS cells expressing 3MST showed that Cys-SSH and GSSH were produced in the presence of physiological concentrations of cysteine and glutathione, while those with longer sulfur chains, Cys-SSnH and GSSnH, were produced in the presence of lower than physiological concentrations of cysteine and glutathione. The present study provides new insights into the production and physiological roles of these persulfurated species as well as the therapeutic targets for diseases in which these molecules are involved.