Fibrous ceria, which is an important ionic material used for solid electrolyte, has been synthesized a new chemical co-precipitation/ripening method. Aqueous nitrate solutions containing NaOH/C6H8 are used to grow various Gd- and Sm-doped CeO2 fibers. The growth mechanism and microstructure properties of the fibers are investigated. Other than fibers, three precipitates either in the forms spherical colloids, flaky, or stick-in-bundle morphologies have also been obtained by similar precursor solutions. The morphologies of those precipitates are greatly affected by the concentration ratio the Ce(NO3)(3)/NaOH/C6H8O7. The fibrous feature is retained by calcination at a temperature up to 1200 in 1h. Reaction kinetics and the chemical composition changes of the fibers are reported. (C) 2009 Elsevier B.V. All rights reserved.