[(CH3S)(3)S](+)SbF6(-), the first example of a trithiosulfonium salt saturated with organyl groups, was prepared from SH3+SbF6-and CH3SCl and characterized by H-1, C-13 NMR, infrared, and Raman spectroscopy. The colorless salt is stable up to 10 degrees C, but solutions in SO;? decompose at -60 OC in a few hours. The structure of the cation was studied by ab initio calculations and a normal coordinate analysis based on four additional isotopic derivates [((CH3S)-S-34)(3)S]+SbF6-, [(CH3S)(3)S-34]+SbF6-, [((CH3S)-C-13)(3)S]+SbF6-, and [(CD3S)(3)S]+SbF6-. The cation possesses C-3 symmetry with a pyramidal trithiosulfonium unit with predicted geometry parameters of r(SS) = 208.8 pm and angle(SSS) = 104.06 degrees.