Experimental and theoretical investigations on the molecular structural, electronic and the vibrational characteristics of 4-hydroxy-1-thiocoumarin are presented. Conformational analysis was carried out to obtain the more stable configuration of the compound. The vibrational frequencies were obtained by DFT/B3LYP calculations employing 6-311++G(d,p), 6-31G(d,p), cc-pVTZ basic sets and B3PW91 method with 6-311++G(d,p) basis set and are compared with FTIR and FT-Raman spectral data recorded in the region of 4000–400 and 4000–100cm −1 , respectively. The total electron density and molecular electrostatic potential surfaces of the molecule were constructed to display electrostatic potential (electron+nuclei) distribution. The electronic properties HOMO and LUMO energies were measured. 1 H and 13 C NMR spectra were recorded and 1 H and 13 C nuclear magnetic resonance chemical shifts of the molecule were calculated by using the Gauge-Independent Atomic Orbital (GIAO) method and analyzed. The picture of localized bonds and lone pairs, stabilization energy of the delocalization of electrons, the charge and hybridisation of the atoms of 4-hydroxy-1-thiocoumarin were clearly explained by NBO analysis.