We comment on the giant electrorheological (ER) activity of high surface area mesoporous cerium-doped TiO2 templated by block copolymer. Our approach of adopting Cole-Cole plot not only fits the dielectric spectra of both mesoporous-doped TiO2 templated ER fluid and single-doped TiO2 ER fluid but also provides a better explanation on their polarizability. (c) 2005 Elsevier B.V. All rights reserved.