Phototriggered linkage isomerization of ruthenium-sulfoxide complexes is one of the few examples of molecular bistability, which is of interest for applications in information and energy storage. Sulfoxide complexes of the type, [M(bpy) 2(L2)] z+(where bpy is 2,2′-bipyridine; M is ruthenium or osmium, L2 is bis-dimethylsulfoxide (dmso), Chloride and dmso, methylsulfonylbenzoate (OSO), dimethylbis(methylsulfinylmethyl)silane (OSSO), or N-benzylidine-2-(ethylsulfinyl)ethanamine (PhNSO)) have been characterized by X-ray crystallography, 1H NMR spectroscopy, electrochemistry, steady-state UV-visible and emission spectroscopy, time-resolved emission, and transient absorption spectroscopy. The ground states of these complexes feature S-bonded sulfoxides. These complexes exhibit strong absorptions in visible region associated with metal-to-ligand charge transfer (MLCT) transitions. Irradiation of the S-bonded complexes within these absorption bands results in a subsequent red-shift in the absorption spectrum of the complex as well as a shift to a lower reduction potential in the electrochemistry. Typically, these values revert at room temperature to the original state. This behavior is interpreted as phototriggered Ru-S → Ru-O and thermal Ru-O → Ru-S intramolecular linkage isomerization. Transient data suggests that this excited-state transformation occurs from an initially formed excited state, prior to population of the 3MLCT excited state or thermal population of ligand field states. Picosecond transient-absorption studies have revealed excited-state O-to-S isomerization process occurring within two of these complexes. For the complex, [Ru(bpy) 2(OSSO)] 2+irradiation of yellow [S,O] with 400 nm light reveals both S-bonded and O-bonded excited states within the instrument response (~750 fs). Irradiation of red [O,O] with 532 nm light reveals both S-bonded an O-bonded excited states within the instrument response (~750 fs). These studies demonstrate two-color femtosecond photonic switching between two excited states. The excited-state reactivity, proposed mechanism of action and an electronic structural diagram of these complexes will be discussed.