Single crystals of ZrW2O8 were prepared by the hydrothermal route followed by a heat treatment at 550 degrees C. XRD, FT-IR, TG-DTA, TEM and SEM were employed to characterize the precursor ZrW2O7(OH)(2)(H2O)(2) and the final product ZrW2O8. The precursor ZrW2O7(OH)(2)(H2O)(2) critically influenced the crystal size of ZrW2O8. The growth of ZrW2O7(OH)(2)(H2O)(2) crystals was restrained with increasing acidity. The addition of ZrW2O8 seeds facilitates and accelerates the nucleation of ZrW2O7(OH)(2)(H2O)(2) crystals. XRD patterns and TEM images showed that ZrW2O7(OH)(2)(H2O)(2) crystals grew under hydrothermal conditions along [2 0 0] and [3 1 0] directions. The pure phase of ZrW2O8 crystals could be obtained by hydrothermal route at the lowest sintering temperature of 300 degrees C. (c) 2005 Elsevier B.V. All rights reserved.