Density functional theory calculations (Becke's three parameter hybrid functional) have been done on a wide range of possible structures for the complexes formed in the reaction between Al3O3- and one or two water molecules. Both energetically competitive structural isomers of Al3O3- (kitelike and distorted rectangle) were considered. The structures of neutral complexes accessed from detachment of the stable anion structures were also optimized. The calculations predict that hydroxide complexes are energetically favored over Lewis acid-base and charge-dipole complexes. For Al3O3-/H2O complexes, the kite-based hydroxide and rectangle-based hydroxide are predicted to be nearly isoenergetic, while for Al3O3-/(H2O)(2), the rectangle-based dihydroxide emerges as being 0.5 eV more stable than the lowest energy kite-based dihydroxide. The structures of these and their neutrals are used to analyze anion PE spectra of Al3O4H2- and Al3O5H4- obtained previously [F. A. Akin and C. C. Jarrold, J. Chem. Phys. 118, 5841 (2003)]. (C) 2004 American Institute of Physics.