Abstract Due to their unique chemical reactivity, transition-metal-doped aluminum oxides have received increased attention. In this work, the influences of metal (Cu, Ag, Au) doping on small (AlO)2 and (AlO)2− rings have been investigated using density functional theory (DFT) and topological analysis of the electron density. The calculated results show that the effects of doping Cu and Ag are similar to those of Au. Thus, Cu and Ag can be used as the substitutions for Au to stabilize the (AlO)2 unit. The doping Cu, Ag, and Au have different influences on (AlO)2 compared to (AlO)2−. Specifically, doping metals enhances the stability of the (AlO)2 unit, whereas it decreases the stability of (AlO)2−. Overall, the effects of metal doping on the (AlO)2− anion are larger than on the neutral (AlO)2 cluster. Finally, the metal-doping decreases the aromaticity of (AlO)2 and (AlO)2− clusters.