Carbon monosulfide (CS) has been a known astromolecule for over three decades, with a pair of initial interstellar detections reported in the early 1970s Penzias et al. and Zuckerman et al., followed by identification in two extragalatic sources, M82 and IC342, by Henkel & Bally in 1985. It was also observed in comet West with UV spectroscopy by Smith et al. Less common isotopic variations (¹³C³²S,¹²C³⁴S) have also been reported. CS is plentiful enough to use as a tracer of structure and temperature of dense clouds ( Taylor et al., Wu & Evans) as well as star-forming regions (Zinchenko et al.).

CS is a periodically related cousin of the most common carbon-bearing astromolecule, carbon monoxide (CO), though CS is more reactive.