A new nonlinear optical material L-valine L-valinium hydrochloride (VHCl) has been synthesized and identified by CHN test, FT-IR spectroscopy and XRD analysis. Formation of new crystal has been confirmed by single crystal X-ray diffraction analysis. VHCl crystallizes in monoclinic system with cell parameters a=11.144(2) angstrom, 6=5.179(9) angstrom, c=13.028(2) angstrom, beta=111.85(3)degrees. Thermal stability of the crystal was investigated using thermogravimetric and differential thermal analysis studies. The suitability of this material for NLO application was studied by optical transmission studies and second harmonic generation (SHG) efficiency measurement by powder method. SHG efficiency of VHCl is found to be comparable to KDP. The molecular geometries and electronic structure of VHCl were calculated at the DFT level using the hybrid exchange-correlation functional, BLYP, PW91, PBE and BP. (C) 2010 Elsevier B.V. All rights reserved.