In this paper, an optimal way to prepare a new material of nano-sized Ce-Zr-Ba mixed oxide powder is firstly reported. It was found that macromolecule surface modified and azeotropy distill treatment are key factors for controlling particle size and increasing surface area. This new preparation method has the advantages of convenience and inexpensive. Under the optimized preparation conditions, the particle size and surface area of obtained powder are 30-50 nm and 119.0 m(2)/g, respectively. The new material of Ce-Zr-Ba mixed oxide offers certain advantages in the use of TWC catalyst. The physical and chemistry properties, crystalline structure, particle sizes, and thermostability are characterized by using XRD, TEM, BET and TGA-DTA techniques. As a comparison, the sample prepared by sol-gel method is also discussed. (C) 2004 Elsevier B.V. All rights reserved.