The solubility of gallium nitride (GaN) in supercritical ammonia with either ammonium bromide (NH(4)Br) or ammonium iodide (NH(4)I) as a mineralizer was evaluated by measuring the weight loss of polycrystalline GaN on dissolution. The solubility of GaN with these mineralizers was compared with that of ammonium chloride (NH(4)Cl). The temperature dependence of the GaN solubility with different mineralizers was in the order NH(4)I > NH(4)Br > NH(4)Cl. At high temperatures a high level of supersaturation was obtained with NH(4)I at a low-temperature difference to NH(4)Cl. These results suggest that use of NH(4)I as a mineralizer could increase the crystal growth rate of GaN. (C) 2011 Elsevier B.V. All rights reserved.