Photoirradiation (lambda > 500 nm) of [{(bpy)(2)Ru(dmbbbpy)}(3)Ru](8+) (1(8+)) (dmbbbpy = 2,2'-bis(N-methylbenzimidazole-2-yl) -4,4'-bipyridine and bpy = 2,2'-bipyridine) in the presence of dimeric N-benzyldihydronicotinamide, (BNA)(2), produced stable two-electron reduced species (1(6+)). Laser flash photolysis and emission spectroscopy were used to understand the reductive reaction pathways. The emission quenching k(q) value (4.1 x 10(9) M-1 s(-1)) obtained from Stern-Volmer plot is in excellent agreement with the electron-transfer rate constant, k(et) (4.7 x 10(9) M-1 s(-1)) determined from the decay kinetics of transient (3)1(8+) triplet-triplet absorption at 650 nm indicating that photoreduction of 1(8+) proceeds via photoinduced electron transfer from (BNA)(2) to (3)1(8+*). After bimolecular electron-transfer process, 1(8+) was reduced to 1(7+) and the electron donor (BNA)(2) was oxidized. Oxidation of (BNA)(2) leads to the formation of highly reactive species, BNA(.) which then reduces 1(7+) to 1(6+). The quantum yield for the formation of the photoreduction product was 0.026.