An amino acid salt L-leucine nitrate (LN) has been synthesized and single crystals were grown by the controlled evaporation of the aqueous solution at constant temperature (30 +/- 0.01) degrees C. The structural and physicochemical properties of the grown crystals were characterized by X-ray powder diffraction and thermal analysis. The optical transmission spectra and second harmonic generation (SHG) were investigated to study its linear and nonlinear optical properties. SHG efficiency is comparable to that of KDP. The dipole moment, polarizability, first order hyperpolarizability and the HOMO-LUMO energy gap of LN were calculated at the framework of Hartree-Fock (HF) and density functional theory (DFT) to confirm the suitability of the crystal for nonlinear optical applications. First hyperpolarizability was found to be 9.4 times of that of urea. (C) 2012 Elsevier B.V. All rights reserved.