Thioxoethenylidene C2S (5), known for its high abundance in interstellar space, has been generated by irradiation of C3S2 (4) and C3OS (6) in an argon matrix at 10 K. Its structural elucidation is based on comparison of the experimental and calculated IR and UV spectra. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)