A new organic salt nonlinear optical crystal, L-arginine trifluoroacetate (L-Arg . CF3COOH, where Arg is NH2C(NH)NH(CH2)(3)CH(NH2)(COOH), abbreviated as LATF), is reported. The material has been synthesized from aqueous solutions. The properties have been determined by elemental analysis, X-ray diffraction, infrared spectroscopy SHG, transmission spectra and optical damage threshold measurements. LATF belongs to the monoclinic crystallographic system, space group P2(1), with a = 10.581(2) Angstrom, b = 5.7100(10) Angstrom, c = 10.861(2) Angstrom, beta = 106.81(3)degrees, z = 2 and V = 628.2(2) Angstrom(3). It exhibits powder SHG efficiencies 2.5 times that of potassium dihydrogen phosphate (KDP), and the ultraviolet transparency cutoff is 232 nm. The optical damage threshold of LATF at 1064 nm is higher than that of LAP and KDP. (C) 2003 Elsevier Science B.V. All rights reserved.