Single crystals of L-histidinium perchlorate (LHPC), a semiorganic nonlinear optical material have been successfully grown from aqueous solution, by slow evaporation solution growth technique. Single crystals in size 5 x 4 x 1 mm(3) were grown in a period of 2 weeks. Single crystal XRD analysis confirmed that the grown crystals are pure form of LHPC. Faces of the crystal were indexed. The mechanical properties of the grown crystal have been studied using Vicker's microhardness tester. Microstructural imperfections of the as grown crystal have been studied. Photoconductivity studies were carried out using Keithley 485 picoammeter. (C) 2004 Published by Elsevier B.V.