L-arginine monohydrochloride monohydrate (LAHCl) single crystals have been implanted with 100 keV H+ ions at different ion fluence ranging from 10(12) to 10(15) ions/cm(2). Implanted LAHCl single crystals have been investigated for property changes. Crystal surface and crystalline perfection of the pristine and implanted crystals were analyzed by atomic force microscope and high-resolution X-ray diffraction studies, respectively. Optical absorption bands induced by colour centers, refractive index and birefringence, mechanical stability and dielectric constant of implanted crystals were studied at different ion fluence and compared with that of pristine LAHCl single crystal. (C) 2011 Elsevier B. V. All rights reserved.