Charge transfer (CT) interactions of the dibutyl ester of N-(4-carboxyphenyl)trimellitimide (NCTD) dissolved in organic solvents have been investigated by means of UV absorption and fluorescence spectroscopy and time-resolved fluorescence measurements. The spectroscopic data are interpreted in connection with quantum mechanical calculations using the AM1 and ZINDO/S method. The electronic transition lowest in energy, observed as an absorption tail in the UV spectra, is interpreted as a direct intramolecular CT excitation from the N-(4-carboxyphenyl) moiety (donor) to the trimellit moiety (acceptor). Independent of the excitation wavelength, a dominant red-shifted CT emission is observed in the fluorescence spectra. Thus, in addition to the direct CT excitation, indirect methods of CT formation exist. In concentrated solutions ground-state stable dimer formation is observed. Direct monomeric CT excitation and ground-state stable dimer excitation takes place in an overlapping energy range. The ground-state stable dimer fluorescence appears blue-shifted with respect to the monomeric CT fluorescence. Ground-state stable dimers exist that have decay times longer than those of the monomeric CT species. As a distribution of decay times is observed in the fluorescence decay curves, dimers with different decay times exist. According to the performed quantum mechanical calculations, dimers with intermolecular CT character are formed.