Electrochemical arylation of cobalt chelates with diphenyliodonium salts occurs at low cathodic potentials (viz., potential of the first reduction wave of the diphenyliodonium salt) and affords the phenyl derivatives of Co-III chelates containing the sigma-Co-C(sp(2)) bond. Nickel complexes should be arylated at higher cathodic potentials because it is necessary to generate paramagnetic Ni-I complexes.