The present work clearly demonstrates the usefulness of fluorescence spectroscopy as a sensitive tool for the study of molecular recognition in solution, whenever, other established experimental techniques are not applicable. Excimer fluorescence spectroscopy was used, in combination with NMR, to study the hydrogen-bonding interactions between a carboxylic group and a nucleic acid base. Two different organic solvents were employed : chloroform, which can participate in II-bonding, albeit weakly, and cyclohexane, which is totally devoid of this ability. The complexes formed between the reactants were determined from the quantitative analysis of the fluorescence and NMR spectra. It was found that in these solutions the predominant H-bonding interactions lead to the formation of the three dimers, acid-base, acid-acid and base-base in order of decreasing strength. The formation of trimeric units, although reported in the literature for similar systems, was not confirmed by our study.