By the fact of finding 43 relationships, we have shown that the reduction potentials, dimerization potentials and potentials in half-equivalent point on titration of aryldiazonium cations XC6H4N+ N (chemical reduction with K-4[Fe(CN)(6)] and TiCl3 in water, (C2H5)(3)N, (-C4H9)(4)N+-OH, CH3OK and C10H8 center dot-Na+ in acetone; polarographic reduction in nitromethane, sulfolane, and N, N-dimethylformamide) are related linearly to the quantum chemically evaluated electron affinities (A) and to the stabilization energies of radicals formed on diazonium cations reduction. Sixty six linear correlations of frequencies (nu) characterizing a collection of bonds stretching vibrations of the C-N+ N fragment in the XC6H4N+ NY- salts with different anions in vaseline oil, N, N-dimethylformamide, acetone, ethylacetate, methanol, water, with the bonds orders of N N and C-N, with the charges on carbon atoms in para positions of the C6H5X molecules aromatic rings, with the mesomeric dipole moments (mu m) of nu substituents have been found. Twelve quantitative relationships combining the m and. quantities with the A values have been established. The interrelations obtained have an explicitly expressed physical meaning, are featured by rather high correlation coefficients and have a predictive power in respect to redox properties, electron affinities, vibrational frequencies of aryldiazonia, as well as to mesomeric dipole moments of atomic groups in organic molecules.