The alternating current (AC) conductivity and dielectric properties of the Co-doped TiO2, were investigated. The temperature dependence of AC conductivity and the parameter s, is reasonably well interpreted by the correlated barrier hopping (CBH) model. The activation energy (E), and the density of states at Fermi level, N(E-1) were determined. The dielectric constant decreases with frequency at low frequencies and increases at high frequencies. (c) 2005 Elsevier B.V. All rights reserved.