Single crystals of L-arginine doped potassium dihydrogen phosphate (KDP) were grown by both conventional and Sankaranarayanan-Ramasamy (SR) methods. The grown crystals were characterized by powder X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, optical transmission, dielectric constant, and Vickers microhardness. The reflectance and extinction coefficients of the grown crystal were calculated and discussed. The variations of dielectric constant, dielectric loss, a.c. resistivity and a.c. conductivity were studied. The lower values of dielectric loss due to fewer defects were observed in SR grown L-arginine doped KDP crystals. Vickers microhardness study showed higher mechanical stability in SR method grown crystals.