Synthesis and single crystal growth of 3-[(1E)-N-ethylethanimidoyl]-4-hydroxy-6-methyl-2H-pyran-2-one by slow evaporation technique is reported. The tautomeric equilibrium, structural and optical characterizations by FT-IR, FT-NMR and UV-Vis-NIR spectral studies are presented. The lattice parameters of the grown crystals are determined by single crystal X-ray diffraction technique. Second harmonic generation efficiency is close to that of urea. (C) 2003 Elsevier B.V. All rights reserved.