Understanding reaction pathways and mechanisms is vitally important for the rational design of catalysts. Towards that end, we developed a method based on a unique combination of mass spectrometry and cryogenic ion vibrational spectroscopy to capture and characterize the reaction complexes formed during homogeneous catalytic processes. In our approach, an in-line electrochemical flow cell is incorporated into an electrospray ionization source, thereby allowing us to controllably form, and mass spectrometrically isolate, the product of each catalytic step. Moreover, the structures of these isolated ions can be directly probed in detail using infrared predissociation spectroscopy. In addition to experimental considerations, this talk will present the application of our approach to model systems as well as to the study of homogeneous catalytic water oxidation by the single metal center [Ru(tpy)(bpy)(H2O)]2+ complex. This talk will also present recent developments that gave us the capability to perform controlled gas-phase chemistry and clustering, which allows us to access unstable reaction species and large solvated complexes.