NIR FT‐Raman and FT‐IR spectra of the non linear optic (NLO) material, Bis (4‐Nitrophenyl) carbonate (BNPC) have been recorded and analyzed. Ab initio quantum chemical computations have been performed at HF/6‐31G(d) level to compute the optimized geometry, vibrational wavenumbers, intensities and first hyperpolarizability. The SHG property is studied by Kurtz‐Perry powder technique. The splitting of the C=O stretching frequency caused by expanded conjugation effects in the carbonate group. The optimized geometry explains that the molecule BNPC is s‐cis‐s‐cis conformation of the carbonate group.