The UV-vis and fluorescence spectra of four monoazo dye derivatives were investigated in the solvents with different polarities. Characterization of UV-vis electronic bands is specified by calculating charge transfer energy (E-CT) and ionization potential (I-p). The solvent effects on the absorption and fluorescence band maxima (V-max) were discussed using the solvent parameters. The magnitude and characteristics of the solute-solvent interactions were determined with multiple linear regression analysis. The Pi-Pi(*) transitions of monoazo derivatives are mainly controlled by global interaction, which is induction-dispersive and orientation interactions. (C) 2012 Elsevier B.V. All rights reserved.