Thiocyanic acic, HSCN, was detected by Halfen et al. in 2009 toward Sgr B2(N) with the 12 m telescope at Kitt Peak in Arizona. Athough some of the eight observed rotational transitions were blended with lines of other species, five consecutive unblended transitions were observed. The spectrum HSCN was characterized experimentally by Brünken et al. HSCN was subsequently detected in TMC-1 as well.

HSCN is an isomeric cousin of isothiocyanic acic, HNCS, which was detected in the late 1970s and is somewhat more stable. The other two isomers, thiofulminic (HCNS) and thioisofulminic (HSNC), are even less stable than HSCN and have been the subject of an unsuccessful search. The abundance ratio [HNCS]/[HSCN] measured with observations by Adande et al. provides insight into the nature of the chemistry that produces the two species.