Bulk single crystals Of L-arginine dihydrate (LAD) were successfully grown from aqueous and mixed solvents by slow cooling and solvent evaporation method. As-grown crystals were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and DTA, TGA analysis. Kurtz powder SHG measurement confirms the nonlinear optical (NLO) property of the as-grown crystals. The crystals possess wide optical transmission window between 200 and 1800nm. (c) 2005 Elsevier B.V. All rights reserved.