Irradiation of the inert complexes [(eta6-arene1)Ru(eta6-arene2)]2+ (arene = benzene, toluene, mesitylene, hexamethylbenzene, anisole, biphenyl, naphthalene, chrysene) in various solvents (H2O/H+, H2O/ H+/EtOH, acetonitrfle, DMSO) leads to the fully solvated complexes [Ru(solvent)6]2+. The reaction occurs in two consecutive steps. The first step is the formation of the intermediate [(eta6-arene)Ru(solvent)3]2+ with either arene1 or arene2 being replaced by solvent. The linear dependence of the observed rate constant for the first step on concentration of solvent as well as reactant is consistent with a second-order reaction. The formation of the half-sandwich intermediates depends on substituents on the arene, irradiation wavelength, temperature, and solvent. The magnitude of the quantum yields PHI(p) is rationalized in terms of steric and electronic effects. The sequence for the release of arenes in the nonsymmetrically substituted complexes as monitored by H-1-NMR is shown to be consistent with a simple MO view, based on overlap strength in the electronic ground state of the starting compound. Luminescence properties of [(C6Me6)2Ru](tos)2 (tos = P-toluenesulfonate) are used for deriving information about the excited state.