The synthesis of the first known mercaptosulfonium salts H3S2+AsF6-, H3S2+SbF6-, and D3S2+AsF6- is reported. The salts were prepared by protonation of H2S2 in the superacidic systems HF-AsF5, HF-SbF5, and DF-AsF5, respectively. The solids decomposed at 213 K under formation of sulfur and H3S+ salts. The mercaptosulfonium salts are characterized by vibrational spectra. An ab initio and a general valence force field were calculated for the H3S2+ cation. The calculations give a conformation with the S-H bond antiperiplanar to the lone pair of SH2+.