A new organic nonlinear optical (NLO) material, L-histidinium tetra fluorophthalate (L-HFP), has been synthesized and grown from water solution by the slow evaporation technique at a growth rate of 0.21 mm/day. The synthesized compound was characterized by elemental analysis, FT-TR and FT-NMR spectral studies. Solubility of L-HFP has been determined and it was found to be very high in water. Single crystals with dimensions 12 x 6 x 3 mm, 3 were grown and subjected to X-ray diffraction analysis to determine the unit cell dimensions and morphology. The microhardness test was carried out in the (100) plane and the load-dependent hardness was measured. The thermal stability of the material was analyzed by TGA and DTA methods. The second harmonic generation efficiency has been measured by the Kurtz powder test. The optical transmittance spectrum shows that the material has a good optical transparency in the entire visible region with a ultraviolet (UV) cutoff wavelength at 230 nm. The laser damage threshold of 56.58 MW/cm(2) has been measured by irradiating the (100) crystal face using a Q-switched Nd:YAG laser (1064 nm). (c) 2005 Elsevier B.V. All rights reserved.