Electrode reduction processes involving the metal salts formation of the dianions of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) were observed using the differential pulse voltammetry. A systematic comparison could be performed through the determination of the association constants of the ion pairing equilibria for a series of alkali and alkaline earth metal cations (M+ and M2+) with DDQ(2-) and TCNQ(2-). TCNQ(2-) was found to have no interactions with M+ and be less reactive with M2+ than DDQ(2-), while their formation potentials are almost similar. This difference was discussed in terms of the charge distributions in the dianion states.