[en] The compound Cs[OCN] has been synthesized and its crystal structure and Raman spectrum were determined on selected single crystals. As postulated in earlier work, the title compound crystallizes isopointal to KN${}_3$ exhibiting the space group I4/mcm (no. 140, Z = 4) with the lattice parameters a = 653.79(2) and c = 799.42(5) pm. The Raman spectrum verified the nature of the triatomic moiety and shows the frequencies typical for an [OCN]${}^{-<!--\; ???\; -->}$ anion with Fermi resonance between the 2δ and the ν${}_{sym}$ vibrations. The undisturbed frequencies and the resulting force constants have been calculated and compared to those of other alkali metal compounds containing comparable linear triatomic anions.