1. A mechanism was proposed for aromatic nucleophilic substitution, which consists in attack of the nucleophile on the substituted bond, with electron transfer to the aromatic substrate and the formation of a pair of free radicals. 2. The probability of the free radicals recombining to the σ-complex decreases with increase in the activity of the nucleophile and the acceptor capacity of the aromatic substrate. 3. The theory was expressed that the formation of free radicals is possible in the coordinated reactions that are forbidden because of the symmetry via one-electron transfer as the result of the convergence of the levels of the boundary orbitals of the reactants.