The electronic spectra of the isomeric naphthaldehydes and acetonaphthones (naphthyl methyl ketones) have been studied in aqueous and hexane media. In the 2-isomers fluorescence originates from the1Lbstate. In the 1-isomers, solvent interactions in the excited state invert the order of states observed in the absorption spectrum so that the1Lastate is lowest. The 2-isomers show normal excited state ionization behavior indicating that these compounds are about 7-8 orders of magnitude more basic in the1Lbstate than in the ground state. The 1-isomers appear to form stoi-chiometric complexes with the protonating species (H3O+) and are truly protonated in the excited state at higher acidities than would be expected. The reasons for this are not understood but the phenomenon appears to have a kinetic rather than a thermodynamic origin.