Diphenyl-tetrazole-5-thione has been synthesized and characterized by X-ray diffraction analysis and FTIR spectra. The extended MO calculations by using density functional theory (DFT) and self-consistent field molecular orbital Hartree-Fock theory with 6-31gG* basis set were carried out. The optimized structure and atomic charge distributions have been investi- gated, showing the exocyclic sulfur atom has the biggest negative charge value and this site is the most likely site of protonation and methylation as well as the potential coordination site with metallic ions. The predicted harmonic vibration frequencies are compared to the experimental values. On the basis of vibrational analyses, the thermodynamic properties of this compound at different temperature have been calculated, revealing the correlations between C0p, m, S0m, H0m and temperature. Diphenyl-tetrazole-5-thione has been synthesized and characterized by X-ray diffraction analysis and FTIR spectra. The extended MO calculations by using density functional theory (DFT) and self-consistent field molecular orbital Hartree-Fock theory with 6-31 gG * The set of structures were carried out. The optimized structure and atomic charge distributions have been investigated, showing the exocyclic sulfur atom has the biggest negative charge value and this site is the most likely site of protonation and methylation as well as the potential coordination site with metallic ions. The predicted vibration vibration frequencies are compared to the experimental values. On the basis of vibrational analyzes, the thermodynamic properties of this compound at different temperatures have been calculated, revealing the correlations between C0p, m, S0m, H0m and temperature.