Crystals L-histidine . HNO3 . H2O, L-histidine . HNO3, L-histidine . 2HNO(3) have been studied by attenuated total reflection Fourier transform infrared (FT-IR ATR) and Fourier transform Raman spectroscopy. Crystal structure of L-histidine-HNO3-H2O has been determined. L-histidine . HNO3 is promising as nonlinear optical material. (c) 2006 Elsevier B.V. All rights reserved.