The linear triatomic species dicarbon sulfide (C₂S) was identified in 1987 in the interstellar cloud TMC-1 by Saito et al. and in the circumstellar shell IRC +10216 by Cernicharo et al. It was suggested by Velusamy et al. that the presence of C₂S in protostellar objects might indicate that they are very young, but later work by Lai & Crutcher and de Gregorio-Monsalvo et al. concluded that most YSOs do not exhibit the molecule.

C₂S is too unstable to exist on earth outside of a laboratory. It is related to another observed astromolecule, C₂O.