Uniform gamma-CuI octahedral crystals with average size of about 15 mu m were prepared by a hydrothermal growth method with sodium citrate (SC). SEM observation shows that the shape evolutions of CuI particles from truncated octahedron to octahedron have been arrested. The additive, sodium citrate, plays an important role in the formation of the uniform gamma-Cul octahedral crystals. (c) 2005 Elsevier Ltd. All rights reserved.