The dielectric properties of the La(2-x)Sr(x)Mo(2)O(9-delta) (x = 0-0.2) ceramics were investigated in the temperature range of 300-800 K. Dielectric measurement reveals that two dielectric anomalies, associated with the oxygen ion diffusion, exist in frequency spectrum with x = 0.5. The broad dielectric peaks in tan delta(omega) can be well fitted by a modified Cole-Cole approach. When x = 0.1, only one dielectric relaxation peak is observed, corresponding to different oxygen ion diffusion processes, as distinct from the only relaxation peak in the pure La(2)Mo(2)O(9). The relaxation parameters To, the dielectric relaxation strength Delta, and the activation energy E(a) were obtained. The result of this work shows that, the conductivity change caused by doping between the two phases is due to the combination of the dipolar effects and motion of ions. (C) 2011 Elsevier Ltd. All rights reserved.