Gallium oxide hydrate (GaOOH) nanorods were prepared through a facile large-scale hydrothermal process from GaCl3-H2O-NaOH solutions under suitable pH conditions. The primary nanoparticles, as crystal nuclei, grew preferentially along the c-axis to become nanorod structures. The aspect ratio of the nanorods could be modulated from 1:7 to 1:15 using the diethyleneglycol (DEG) and water mixed solvent. The pH value variation in water resulted in different nucleation rates, which further resulted in different structures from quadrilateral nanorods to nanorods arrays. Calcination of the GaOOH nanorods at 900 degrees C in air yielded gallium oxide (beta-Ga2O3) crystals with a similar morphology. The beta-Ga2O3 nanorods had shown a broad blue emission peak at 455 nm with an average lifetime of 64 ns when excited at 254 nm ultraviolet (UV) light at room temperature. (c) 2005 Elsevier B.V. All rights reserved.