Aluminum oxide (Al(2)O(3)) films have been deposited on lithium niobate (LiNbO(3)) substrates by electron beam evaporation without any interlayer between them to ensure a good adhesion of the Al(2)O(3) films to LiNbO(3) substrates. As Al(2)O(3) thin films can sufficiently increase the surface acoustic wave (SAW) velocity, they can be used to improve the performance of the SAW device. The SAW phase velocity in the Al(2)O(3)LiNbO(3) structure was found to increase with the insertion of an Al(2)O(3) film, which can be attributed to the stiffening effect of the Al(2)O(3) layer. The velocity change ratio of SAW was about 4.39% (at 304 MHz) for the Al(2)O(3) (9.7 pin)/LiNbO(3) sample. A comparison with other findings in literature reveals that this result is better than what is available from diamond-like carbon/SiC buffer layer/LiNbO(3) structure, whose the velocity change ratio is 2%. (C) 2010 Elsevier B.V. All rights reserved.