The experimental results of optical, thermal, mechanical and chemical etch pit studies of nonlinear optical crystal L-arginine acetate (LAA) are presented. Quality of the grown crystal is considerable good as observed from the etch pit density (10(4) cm(-2)). LAA has a wide optical transmission window between 220 and 1500 nm. Its optical damage threshold and SHG efficiency is comparable with that of KDR Hardness of LAA is anisotropic in nature depending on both direction and plane of indentation and (010) (203) is the hardest plane and direction combination. The obtained results of Young's modulus calculated from ultrasonic velocity data and microhardness measurement confirmed the applicability of Marshall law for soft crystal category. (c) 2004 Elsevier B.V. All rights reserved.