The methods of calculation of the equilibrium constants and electronic absorption spectra of charge-transfer complexes are discussed with special emphasis on the treatment of the contact interaction. In particular, a model for the pseudo-equilibrium of contact complexes is developed. It is shown that a small but nonzero effective equilibrium constant can be defined for contact pairs and all higher order contact complexes. The results are applied to the study of the interaction of C-60 and C-70 with naphthalene and 1-methylnaphthalene, with the main goal being to establish the nature of the interaction of the fullerenes with these aromatic hydrocarbons. It is concluded that only simple contact complexes are formed, for which several spectroscopic parameters are obtained.