In this work, we reported a combined experimental and theoretical study on molecular structure and vibrational analysis of 2-chloro-5-nitrotoluene (2Cl5NT). The Fourier transform infrared and FT-Raman was recorded in the solid phase. The molecular geometry and vibrational frequencies of 2Cl5NT in the ground state have been calculated by using ab initio HF and density functional method (B3LYP) with 6-311++G(d,p) as basis set. Comparison of the observed fundamental vibrational frequencies of 2Cl5NT with calculated results by density functional methods indicates that B3LYP/6-311++G (d,p) is superior to other methods for molecular vibrational problems. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. The thermodynamic functions of the title compound was also performed at B3LYP/6-311++G(d,p) level of theory. A detailed interpretation of the infrared spectra of 2Cl5NT was also reported. The theoretical spectrograms for FTIR and FT-Raman spectra of the title molecule have been constructed. Time depended B3LYP (TD-B3LYP) calculations of electronic absorption spectrum were performed on the optimized structures at the same 6-31G++(d,p) basis set for elaborate usage in pharmaceutical application.