New nonlinear optical (NLO) single crystal of (L)-threonium acetate was grown by slow evaporation and temperature lowering methods from aqueous solution. The grown crystals were characterized by X-ray diffractometry (XRD), UV-vis-NIR, Fourier Transform infrared (FTIR) and mass spectral analysis. XRD and FTIR studies reveal that the (L)-threonine: acetic acid stoichiornetry is equal to 1:1. Transmittance spectrum of the crystal shows complete transparency even in the NIR region. Mass spectrometry of the crystalline compound confirms the molecular weight of the title crystal. The NLO property of the grown crystal has been confirmed by Kurtz-powder second harmonic generation (SHG) test and its SHG efficiency was found as d(eff) = 1.14 d(eff) (KDP). (c) 2005 Elsevier B.V. All rights reserved.