The adsorption and diffusion of silver adatoms is examined over different partially hydroxylated model alpha-Al2O3(0001) surfaces created by combinations of quadrants of the two stable phases, a fully hydroxylated surface and the Al-terminated surface. While the model shows relatively weak adsorption which leads to low activation barriers for diffusion, it does not fully capture the behavior observed in XPS experiments by Kelber et al. which report a stronger interaction with the support and an increase in the diffusion barrier when partially hydroxylated surfaces are created. It is suggested that some as of yet uncharacterized defects must be responsible for the observed behavior. (c) 2007 Elsevier B.V. All rights reserved.