Emission, excitation spectra, quantum yields, and emission lifetimes are reported for the mixed-ligand, bis (2.2'bipyridine)ruthenium-(II) complexes, cis-[Ru(bpy)(2)(PPh(3))X](n+) with X = Cl(-), Br(-), CN(-), and NO(2)(-) (n = 1) and pyridine (py), 4-aminopyridine (NH(2py)), 4,4'-bipyridine (4,4'-bpy), NH(3), and MeCN (n = 2) in EtOH-MeOH, 4:1 (v:v), at 77 K. Radiative, k(r), and nonradiative, k(nr), decay rate constants were determined for the series of complexes, and a linear dependence of In k(nr), on E(00), with E(00) being the 0-0 energy gap determined by emission spectral fitting, was obtained with a slope of -(0.6 +/- 0.1) x 10(-3). On the basis of emission quantum yields and apparent kr values, possible metal-to-ligand charge-transfer (MLCT) deactivation by direct population of excited (1)dd states from initially excited (1)MLCT states is discussed.