L-Alanine single crystals have been grown from H2O and D2P by slow evaporation and temperature lowering methods. The grown crystals were characterized by powder X-ray diffraction analysis and the vibrational frequencies of various functional groups in the crystals have been derived from FTIR spectrum. Optical transparency of the grown crystals was investigated by UV-vis-NIR spectrum. Differential scanning calorimetry (DSC) was carried out to investigate the thermal stability of the grown crystals The NLO property of the grown crystal has also been confirmed by the Kurtz-powder SHG test. (C) 2008 Elsevier B.V. All rights reserved.