O-Ethyl benzoylthiocarbamate has been synthesized and characterized by elemental analysis and FT-IR. The crystal structure was determined by X-ray diffraction analysis. Title compound crystallizes in the orthorhombic space group Pna2₁, with Z=4. Unit cell parameters a=9.941(3)Å, b=9.352(3)Å, c=10.962(3)Å and V=1019.1(5)ų. The molecular geometry and vibrational frequencies of O-ethyl benzoylthiocarbamate in the ground state has been calculated using the Hartree–Fock and density functional using Becke's three-parameter hybrid method with the Lee, Yang, and Parr correlation functional (B3LYP) methods with 3-21G and 6-31G(d) basis sets. The computational frequencies are in good agreement with the observed results. Comparison of the observed fundamental vibrational frequencies of O-ethyl benzoylthiocarbamate and calculated results by density functional B3LYP and Hartree–Fock methods indicate that B3LYP is superior to the scaled Hartree–Fock approach for molecular vibrational problems.