The energies of instantaneous electron detachment ( I i v ) from guaiacol, vanillin, vanillyl alcohol, α-guaiacylpropanone molecules and phenolate anions of guaiacol and vanillyl alcohol corresponding to the first two peaks in the photoelectron spectra of these compounds in the gas phase, and the change ( δI i v ) in I i v due to the solvent effect were calculated by using the semiempirical SCF MO LCAO method in the framework of the CNDO/S3′ approximation. Each atom in the chemical compound was characterized by the average charge, charge dispersion and a certain Onsager radius. Solvents (water, acetonitrile, acetone, ethanol, dioxane, dimethyl sulphoxide) were characterized by the experimental values of the refractive index and dielectric constant. The reaction field strength and effective Onsager radius ϱ(X) of each molecule X in a given solvent were calculated in terms of the computed increase of the molecular dipole moment in solution and of its dipole polarizability tensor.