The present investigation is focused on to identified the linear and non linear optical qualities of the well known nlo crystal l-Histidinium 2-nitrobenzoate. The optical quantities such as reflection, refractive index and optical band gap have been evaluated using UV- Visible absorption spectrum. The birefringence nature of the crystal was examined. Photo luminous studies were carried out to find the optical emission of the crystal. Optical limiting method was involved and the linear absorption co efficient was calculated. Z-scan measurements reveal the third order non linear optical property of the crystal.