UV-visible spectra, emission spectra, and RU(III/II) reduction potentials have been measured for cis[Ru(bpy)(2)(py)(CN)](+) (bpy is 2,2’-bipyridine; py is pyridine), cis-Ru(bpy)(2)(CN)(2), [Ru(tpy)(CN)(3)](-) (tpy is 2,2’ : 6’,2"-terpyridine), [Ru(bpy)(CN)(4)](2-), and [Ru(MQ(+))(CN)(5)](2-) (MQ(+) is N-methyl-4,4’-bipyridinium cation) in twelve solvents. The shifts in the metal-to-ligand charge transfer (MLCT) absorption (E(abs)) or emission (E(em)) band energies with solvent increase linearly with the number of cyano ligands and correlate well with the Gutmann "acceptor number" of the solvent. Intraligand pi --> pi* band energies also correlate with acceptor number, but with only similar to 30% of the shifts for the MLCT bands, The solvent dependence arises through mixing of the pi --> pi* transitions with lower energy MLCT transitions. MLCT absorption and emission spectra are convolutions of overlapping vibronic components, and a Franck-Condon analysis of emission spectral profiles for cis-Ru(bpy)(2)(CN)(2)* has been used to evaluate the energy gap, E(0), and chi’(0.gs), where chi’(0.gs) is the sum of the solvent reorganizational energy for the ground state below the excited state and the inner-sphere reorganizational energy of the low-frequency modes, chi(i,L), is treated classically. Both E(0) and chi’(0.gs) correlate well with acceptor number with Delta E(0)/Delta AN = 44 +/- 2 cm(-1)/AN unit and Delta chi(0.gs)/AN 21 +/- 3 cm(-1)/AN unit if it is assumed that chi(i,L) is solvent independent. : 6’,2"-terpyridine), [Ru(bpy)(CN)(4)](2-), and [Ru(MQ(+))(CN)(5)](2-) (MQ(+) is N-methyl-4,4’-bipyridinium cation) in twelve solvents. The shifts in the metal-to-ligand charge transfer (MLCT) absorption (E(abs)) or emission (E(em)) band energies with solvent increase linearly with the number of cyano ligands and correlate well with the Gutmann "acceptor number" of the solvent. Intraligand pi --> pi* band energies also correlate with acceptor number, but with only similar to 30% of the shifts for the MLCT bands, The solvent dependence arises through mixing of the pi --> pi* transitions with lower energy MLCT transitions. MLCT absorption and emission spectra are convolutions of overlapping vibronic components, and a Franck-Condon analysis of emission spectral profiles for cis-Ru(bpy)(2)(CN)(2)* has been used to evaluate the energy gap, E(0), and chi’(0.gs), where chi’(0.gs) is the sum of the solvent reorganizational energy for the ground state below the excited state and the inner-sphere reorganizational energy of the low-frequency modes, chi(i,L), is treated classically. Both E(0) and chi’(0.gs) correlate well with acceptor number with Delta E(0)/Delta AN = 44 +/- 2 cm(-1)/AN unit and Delta chi(0.gs)/AN 21 +/- 3 cm(-1)/AN unit if it is assumed that chi(i,L) is solvent independent.