Single crystals of N-(2-hydroxybenzylidene)acetohydrazide were grown by evaporating the solvents from a methanol solution. The single crystal X-ray structure solution confirmed the monoclinic system of the compound with P2(1)/n space group. The functional groups were identified using FT-IR spectroscopic technique. H-1 NMR spectral analysis were carried out to identify the position of protons. The optical properties such as UV-vis in transmittance mode and second harmonic generation (SHG) conversion efficiency were investigated to explore the nonlinear optical (NLO) characteristics of the above crystals. In addition, the thermal properties of the title crystal were also evaluated with thermogravimetrical analysis. (C) 2011 Elsevier BM. All rights reserved.