Luminescent bimolecular and termolecular exciplexes of * [Ru(bpy) 3 ] 2− and * [Ru(phen) 3 ] 2+ (bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline) formed by silver ions have been characterized and compared. Formation constants, luminescence lifetime, radiative and non-radiative decay constants were determined at room temperature. Oxidative quenching measurements in the [Ru(bpy) 3 ] 2− —Ag + system using MV 2+ (MV 2+ = 1,1'-dimethyl-4,4'-bipyridinium) as an electron acceptor resulted in quenching rate constants, (3.1 ± 0.2) × 10 9 , (3.1 ± 0.3) × 10 9 , (1.6 ± 0.3) × 10 9 and cage escape efficiencies, 0.11 ± 0.01, 0.05 ± 0.01, 0.06 ± 0.01, for * [Ru(bpy) 3 ] 2+ , * [Ru(bpy) 3 ]Ag 3+ and * [Ru(bpy) 3 ]Ag 2 4+ , respectively. Temperature-dependent luminescence lifetime measurements in aqueous solutions revealed that the exciplex formation causes a considerable change in the deactivation pathways of the excited species. Exciplex formation results in a decrease in the efficiency of the thermally activated decay through MLCT å dd transition and in an increase of the efficiency of deactivation to the ground state via other non radiative processes. The thermodynamic parameters of the exciplex formation have been estimated.