Mesoporous TiO(2)/polypyrrole (PPy)-based nanocomposite for electrorheological fluid was synthesized through one-pot method. By exploiting the combination conductivity of PPy and high dielectric constant of TiO(2), the ER fluid exhibited an enhanced effect. The shear stress was 3.3 times as high as that of mesoporous TiO(2). Powder X-ray diffraction (XRD), TEM and Fourier transform infrared (FT-IR) spectroscopy were employed to characterize the as-made samples. Using a modified rotational viscometer, the electrorheological effect was measured. Dielectric spectra were also given to explain the mechanism. (c) 2008 Published by Elsevier Ltd.