Good quality ammonium dihydrogen phosphate single crystals have been grown by: (i) Sankaranarayanan-Ramasamy (SR) method and (ii) SR method with slotted ampoule. The grown crystals were subjected to UV-Vis spectroscopy, high-resolution X-ray diffractometer, dielectric, piezoelectric and laser damage threshold studies. Compared to the (1 0 0) plane of the conventional method grown ADP crystal and < 1 0 0 > directed SR method grown ADP crystal, the crystal grown by SR method with slotted ampoule has higher growth rate, higher optical transparency, high crystalline perfection, low dielectric loss, high piezoelectric charge coefficient and high laser damage threshold due to diffusion of segregated impurities away from the growing crystal in the slotted ampoule growth. (C) 2010 Elsevier B.V. All rights reserved.