Single crystals of L-argininium dinitrate (LADN), a semiorganic nonlinear optical (NLO) material have been successfully grown by slow solvent evaporation technique. Good optical quality single crystals with dimensions tip to 28 x 8 x 1 mm(3) were obtained. The crystals were characterized by optical absorption spectrum, FTIR and X-ray diffraction studies. The optical absorption spectrum shows that the absorption in LADN is nearly equal to zero in the entire visible region. The thermal stability of the crystal was Studied by DTA and TGA. (c) 2005 Elsevier B.V. All rights reserved.