Formamidinate-bridged Rh-2(II,II) complexes containing diimine ligands of the formula cis- [Rh-2(II,II)(mu-DTolF)(2) (NN)(2)](2+) (Rh-2-NN2), where DTolF = p-ditolylformamidinate and NN = dppn (benzo [i] dipyrido [3,2-a:2',3'-4]quinoxaline), dppz (dipyrido[3,2-a:2',3'-c]phenazine), and phen (1,10-phenanthroline), electrocatalytically reduce H+ to H-2 in DMF solutions containing CH3COOH at a glassy carbon electrode. Cathodic scans in the absence of acid display a Rh-III,Rh-II/II,Rh-II reduction at -0.90 V vs Fc(+)/Fc followed by NN0/- reduction at -1.13, -1.36, and -1.65 V for Rh-2-dppn(2), Rh-2-dppz(2), and Rh-2-phen(2), respectively. Upon the addition of acid, Rh(2)dppn(2) and Rh-2-dppz(2) undergo reduction-protonation-reduction at each pyrazine-containing NN figand prior to the Rh-2(II,II/II,I) reduction. The Rh-2(II,I) species is then protonated at one of the metal centers, resulting in the formation of the corresponding Rh-2(II,III)-hydride. In the case of Rh-2-phen(2), the reduction of the phen ligand is followed by intramolecular electron transfer to the Rh-2(II,II) core in the presence of protons to form a Rh-2(II,III)-hydride species. Further reduction and protonation at the Rh-2 core for all three complexes rapidly catalyzes H-2 formation with varied calculated turnover frequencies (TOF) and overpotential values (eta): 2.6 X 10(4)s(-1) and 0.56 V for Rh-2-dppn, 2.8 X 10(4) s(-1) and 0.50 V for Rh-2-dppz(2), and 5.9 X 10(4)s(-1) and 0.64 V for Rh-2-phen(2). Bulk electrolysis confirmed H-2 formation, and further CH3COOH addition regenerates H-2 production, attesting to the robust nature of the architecture. The cis-[Rh-2(II,II)(mu-DTolF)(2)(NN)(2)](2+) architecture benefits by combining electron-rich formamidinate bridges, a redox-active Rh-2(II,II) core, and electron-accepting NN diimh e ligands to allow for the electrocatalysis of H+ substrate to H-2 fuel.