The organic salt of Benzimidazolium L-aspartate (BLA) has been synthesised and single crystals were grown by slow evaporation solution growth technique at room temperature using water as the solvent. The grown crystal was subjected to single crystal X-ray diffraction analysis and confirmed it belongs to monoclinic crystal system with space group P2(1)/c. The crystalline perfection was studied using High resolution X-ray diffraction (HRXRD). The functional groups were analysed by FT-IR analysis. The optical transmittance and the lower cut-off wavelength of the BLA crystal have been identified by UV-Vis study. The thermal stability of the title crystal was investigated by TGA/DTA analyses. The Vickers microhardness analysis was carried out to study the mechanical strength of the crystal. The dielectric response of the crystal was studied in the frequency range 100 to 5 MHz at different temperatures. The surface morphology of the grown BLA crystal was studied by scanning electron microscopy (SEM). The second harmonic generation efficiency was measured in comparison with KDP by employing Kurtz Perry Powder method.