Recently, X-ray diffraction (XRD) and scanning tunneling microscopy (STM) experiments confirmed a theoretical prediction that the surface of the two O-layer. or 5 Angstrom, alumina film on NiAl(110) has 50% tetrahedral and 50% octahedral Al-site occupancy, a distorted A-plane of kappa-alumina. Now density functional theory (DFT) calculations for a 7 Angstrom (i.e., three oxygen layer) alumina film are compared with experiments on Ni3Al(110). To minimize the surface energy, we assume that the first two planes of the thicker film are the A- and B- planes of the K-phase. As with the thinner film, significant distortions occur from the crystalline form. However, a 2 x 1 unit cell occurs with rows separated by similar to1 nm. STM of this film confirms this structure. Finally, an earlier theoretical conjecture is confirmed using low energy electron diffraction (LEED) on the same film: the bottom oxygen layer is chernisorbed on a plane of Al(111), and these are rotated against the substrate to produce the observed domain structures. Thus this system is tri-layered as kappa-alumina (A-B planes)/O(111) on Al(111)/Ni3Al. (C) 2004 Elsevier B.V. All rights reserved.