Charged transient species produced from high-frequency discharge Of CS2 have been trapped in solid argon and neon. Besides the previously identified CS2-, CS2+, and (CS2)(2)(+) species, new absorptions at 909.0 cm(-1) in solid neon and 908.0 cm(-1) in solid argon were observed. Isotopic substitutions ((CS2)-C-13, (CS2)-S-34, and mixtures) showed that the new species involves two equivalent CS2 subunits. The photosensitive behavior and the agreement with frequencies and isotopic frequency ratios from quantum chemical calculations substantiate assignment of these absorptions to the most stable isomer of the (CS2)(2)(-) anion, which was predicted to have a planar C-C chemically bonded D-2h structure.