Uniform octahedral YVO4:Eu3+ microcrystals have been successfully prepared through a designed two-step hydrothermal conversion method. One-dimensional precursor Y4O(OH)(9)NO3 was first prepared through a simple hydrothermal process without using any surfactant, catalyst or template. Subsequently, well-defined octahedral YVO4 was synthesized at the expense of the precursor during a hydrothermal conversion process. XRD results demonstrate that the diffraction peaks of the final product can be well indexed to the pure tetragonal phase of YVO4. The SEM and TEM images indicate that the as-prepared YVO4 sample has regular octahedral shape with sharp corners and well-defined edges. The as-obtained YVO4:Eu3+ phosphor shows strong red emission under ultraviolet excitation or low-voltage electron beam excitation. Furthermore, this facile and general conversion method may be of much significance in the synthesis of many other lanthanide compounds with uniform morphology. (C) 2009 Elsevier B.V. All rights reserved.