Semi organic nonlinear optical (NLO) crystal L-Lysine 4-nitrophenol (LLPNP) monohydrate was grown by slow evaporation technique. The grown LLPNP crystal was subjected to single crystal X-ray diffraction. Solubility of the LLPNP was carried out for different temperature. Thermal stability of the grown material was carried out by TG/DTA analysis. The hardness of the material was found by Vickers micro hardness technique. Laser damage threshold value was determined by Nd: YAG laser. SHG efficiency was determined by Kurtz Perry Powder SHG technique.