In the present work, an aim is to investigate the influence of l-Ornithine monohydrochloride (LOMHCl) doping on structural, optical and electrical properties of pure ADP crystals. It is analyzed by following various characterizations. Pure and LOMHCl doped ammonium dihydrogen phosphate (ADP) crystals have been grown by using slow solvent evaporation technique at room temperature in dust free laboratory. The powder XRD patterns show the single phase nature of pure and doped ADP crystals. The average crystallite size and strain are found from X-ray peak broadening analysis. The UV–Vis spectra indicate slight decrement in the transmittance and band gap values of doped ADP crystals. The SHG efficiency of doped ADP crystals found to increase compared to pure ADP and pure KDP. Z-scan analysis shows increased nonlinear optical properties of doped ADP crystals. The dielectric constant and loss plots show usual behavior with respect to frequency and reduction in the values of doped ADP. The Jonscher's power is studied for ac conductivity. The complex impedance and modulus plots show single semicircle for both pure and doped ADP due to grain contribution only. The stretch exponent parameter values indicate the non-Debye type relaxation process.