Dilute (3.8 at.%) cobalt- doped ZnO thin films are deposited on LiTaO3 (LT) substrates with three different orientations [LT(1 1 0), LT(0 1 2) and LT(0 1 8)] by direct current reactive magnetron co-sputtering. The experimental results indicate that Co atoms with 2+ chemical valence are successfully incorporated into the ZnO host matrix on various oriented substrates, and the substrate orientations have a profound influence on the crystal growth and magnetization of Co: ZnO films. A large magnetic moment of 2.42 mu(B)/Co at room temperature is obtained in the film deposited on LT(0 1 2), while the corresponding values of the other films deposited on LT(1 1 0) and LT(0 1 8) are 1.21 mu(B)/Co and 0.65 mu(B)/Co, respectively. Furthermore, the crystal growth mode of Co: ZnO films on various oriented LT, the relationship between the microstructures and corresponding ferromagnetic properties are also discussed. (c) 2007 Elsevier B.V. All rights reserved.