Two groups are credited with the first observations of tricarbon monosulfide (C₃S) in 1987. Using new laboratory data, Yamamoto et al. identified three unknown lines in observations of TMC-1 by Kaifu et al. captured with the 45 m telescope at the Nobeyama Radio Observatory. Cernicharo et al. observed 11 lines of C₃S in IRC +10216 with the IRAM 30 m telescope. The detection in IRC +10216 was confirmed in 1993 by Bell et al. Tercero et al. reported the first detection of C₃S in a warm cloud, Orion KL, in 2010.

Tricarbon monosulfide and dicarbon monosulfide (C₂S) are the only thiocumulene compounds that have been detected to date, although experimental measurements of rotational spectra have been made for compounds with up to nine carbon atoms.