Highly c-axis oriented aluminum nitride (AIN) films were deposited on z-cut LiNbO3 substrates by reactive rf magnetron sputtering. The crystalline properties investigated by X-ray diffraction (XRD) revealed that AIN film with (002) preferred orientation was improved by an increase of the deposition time within the experimental range. However, the surface morphology of AIN film measured by scanning probe microscopy (SPM) showed that the roughness was getting worse with increase of deposition time. Surface acoustic wave (SAW) properties, measured by a network analyzer in the structure consisting of highly c-axis AIN films on z-cut LiNbO3 substrates, were investigated. The phase velocity (V-p) was significantly increased by the increase of h/lambda, where h is the thickness of AIN film and A is the wavelength. However, the insertion loss (IL) of SAW filters was also increased by the increase of h/lambda. Experimental results on the temperature characteristics of SAW devices are also presented. (C) 2004 Elsevier B.V. All rights reserved.