Semiorganic single crystals of l-histidine and l-histidine hydrochloride monohydrate have been obtained in a single solution prepared from the mixture of l-histidine and hydrochloric acid in 1:2 M ratio. Growth aspects of the single crystals have been discussed along with characterization studies. Crystal system and lattice parameters have been identified by X-ray diffraction analyses. It has been observed that the grown crystals possess orthorhombic system but with different set of lattice parameters. Presence of various functional groups has been identified and formation of two different crystals has been confirmed by Fourier transform infrared spectral analyses and FT-Raman studies. Linear and nonlinear optical properties have been studied by UV-Vis spectral analyses and Kurtz-Perry powder technique respectively. The thermal stability of the grown crystals was determined by thermal analyses. From the characterization studies it is found that both the crystals are useful for second harmonic generation applications. © 2013 Elsevier B.V. All rights reserved.