Abstract This research contributes valuable insights into the understanding of third-order nonlinear optical effects in L-histidine hydrochloride monohydrate (LHHC) single crystal, offering a foundation for future work in optimizing its properties for practical applications in the field of nonlinear optics. It presents a systematic analysis into the LHHC crystal properties harvested by slow evaporation solution (SEST) method. Originally, structure of the compound was confirmed through powder X-ray diffraction analysis. FTIR analysis was performed to get information about molecular composition of the compound. The assessment of the optical quality of LHHC single crystal was done by UV–Vis and photoluminescence spectroscopies. TG-DTA was employed to assess the stability of the single crystal under different temperature conditions. Z-scan technique, with an open aperture (OA) & closed aperture (CA) configuration, was employed to comprehensively explore the third-order nonlinear response of LHHC single crystal.