The absorption and fluorescence spectral characteristics of dibenzofuran-2-carboxylic acid (DBFCA) have been studied in aqueous solutions and in several organic solvents. The fluorescence emission is structured both at basic pH and in nonaqueous media, whereas at acidic pH it is broad and largely Stokes-shifted. The red-shifted emission emerges solely as a consequence of an intramolecular charge-transfer (ICT) state, stabilized by hydrogen bonding with the solvent, and is not due to changes in the molecular structure upon excitation, to excimer emission, or to any other multimolecular processes. The pK's in the ground and first electronic excited states are pK = 4.19 and pK* = 8.5, as calculated by the Forster cycle from the absorptometric and fluorimetric data. DBFCA forms inclusion complexes with alpha-, beta-, and gamma-cyclodextrins (CDs), with the spectral behavior being very dependent on the type of CD and pH. At alkaline pH, only the beta- and gamma-CDs form complexes, with a 1:1 stoichiometry. H-1 NMR spectra point to the most likely structure of the complex in solution, with the carboxylate group located at the narrower end of the CD. The observed fluorescence quenching is static in nature, as deduced from the temperature dependence of the emission and from the absorption spectra. The decrease in fluorescence has been used to assess the formation constants by nonlinear regression analysis, and from their dependence on the temperature, the thermodynamic parameters of the binding, enthalpy, and entropy have been deduced. At acidic pH, fluorescence enhancement occurs with alpha- and beta-CDs, and DBFCA forms complexes more stable than those at alkaline conditions with all the CDs. gamma-CD induces the formation of an excimer of 2:1 stoichiometry, DBFCA(2):gamma-CD. The effect of the -COOH group on the stability is analyzed by comparing the DBFCA complexes with those formed with the nonsubstituted dibenzofuran (DBF).