[en] Thermodynamic functions (ΔG_f and ΔH_f) of clorinated dibenzo-p-dioxins (Cl_nDD) with n = 0–8 were calculated at the DFT level of theory using the B3LYP functional and extended 6–31** basis sets and used to analyze possible relationship of the structures and energy characteristics of these compounds with their toxicity. A new sequence of successive isodesmic reactions, which makes it possible to calculate chemical potentials μ_G and μ_H from the ΔG_f and ΔH_f values, has been proposed. In the framework of this approach, satisfactory linear correlations between the chemical potentials μ and the logarithms of toxicity of the corresponding polychlorodioxins were obtained for the first time.