The correlation between the ionic conductivity and the nano-crystallization processes of (CuI)(x)-(Cu2MoO4)(1-x) superionic conducting glasses has been systematically investigated by X-ray diffraction and high-resolution transmission electron microscopy (HREM). In x=0.52, CuI crystal precipitates as a primary phase. On the other hand, in x=0.40, crystallization from homogeneous glass into CuI crystal and other phase has been observed. Nano-crystallization processes depend on CuI content. The difference of the nano-crystallization processes influences the electrical conductivity. (c) 2006 Elsevier B.V. All rights reserved.