The adsorption of twenty-four aromatic pollutants (1,3-dichlorobenzene, benzene, ethyl benzene, 1,4-dinitrobenzene, 4-fluorophenol, phenyl acetate, etc.) onto B12N12 and Al12N12 nanocages is studied using density functional theory. The pollutant molecules are typically bound to the B/Al atoms of the B12N12 and Al12N12 nanocages. Benzene and chlorine−/alkyl-substituted benzenes are observed to be weakly adsorbed on the B12N12 and Al12N12 nanocages. All other pollutant molecules are strongly adsorbed on the B12N12 and Al12N12 nanocages. Importantly, the adsorption energies are linearly proportional to the MESP minimum values of the pollutant molecules. A striking change in the reactivity parameter (e.g. global electrophilicity) of the B12N12 and Al12N12 nanocages is usually found for the adsorption of nitro-substituted aromatic compounds and carbonyl-containing compounds. The QTAIM analyses point to a noncovalent character for the interaction of benzene and chlorine−/alkyl-substituted benzenes with the B12N12 nanocage, and to a partial covalent character for the interaction of the other studied pollutant molecules with the B12N12 nanocage. However, an opposite trend is observed for the pollutant/Al12N12 system. Our results show a relatively high stability of the complexes of nitro-/OH−/carbonyl-containing compounds with B12N12 and Al12N12 in water.