Single crystals of Diglycine Picrate (DGLP) were grown by slow evaporation technique and the vibrational spectral analysis is carried out using FT Raman and FT-IR spectroscopy, supported by Density Functional Theoretical (DFT) computations to derive equilibrium geometry, vibrational wavenumbers and first hyperpolarizability. The vibrational spectra confirm the existence of NH 3 + in DGLP. The influence of Twisted Intramolecular Charge Transfer (TICT) caused by the strong ionic ground state hydrogen bonding between charged species making DGLP crystal to have the non-centrosymmetric structure has been discussed. The Natural Bond Orbital (NBO) analysis confirms the occurrence of strong intermolecular NH⋯O hydrogen bond. The HOMO–LUMO energy gap and the first order hyperpolarizability were calculated and it supports the nonlinear optical activity of the Diglycine Picrate crystal.