Uniform-sized monodisperse cerium dioxide nanocubes with 20-120 nm edge lengths can be synthesized by an inexpensive microwave-assisted method. This is based on the oxidation and then decomposition of cerium (III) nitrate aqueous solution under a basic environment. The high energy emitted by microwave irradiation at a short time can promote the reaction and the crystallization process Simultaneously. Both shape and size of the cerium oxide could be tuned more conveniently by changing the concentration of surfactant in the solution and the power of the microwave irradiation. The morphology and crystal structure of cerium dioxide nanocubes obtained at different conditions were characterized by high-resolution transmission electron microscope, X-ray diffraction and selected area electron diffraction. (C) 2008 Elsevier B.V. All rights reserved.