The effect of specific hydrogen-bonding interactions on the electronic spectra and the infrared (IR) absorption spectra of several naphthol-type photoacids was investigated. A correlation between the pK a * of the photoacid and its optical solvatochromism was observed for R*O H...B-type hydrogen bonds using the Kamlet-Taft (K-T) analysis. In addition, a correlation between the spectral shift in the IR stretching frequency of the RO H...B bond and the optical Stokes shift in the fluorescence spectra of the photoacids was found.