Interfaces play a dominant role in molecular science. Heterogeneous catalysis is the prime example where reactions are accelerated due to the presence of surfaces including catalytically active liquid/solid interfaces. Within the last decades, surface science has triggered an impressive boost in the molecular understanding of catalytic processes. However, so far this has mainly been restricted to reactions at the gas-solid interface. Close to nothing is known about how reactants get de-solvated, intermediates stabilized, and products re-solvated along catalytic cycles at liquid-solid interfaces. It is unclear which of the concepts developed for gas-solid interfaces – if any – can be transferred to solvated interfaces. Even less understood are electrocatalytic reactions at electrified interfaces. What are the factors that quantify the rates of such universally important reactions? This seemingly simple question is far from being answered. The scientific challenge arises from the strong influence of the solvent. Improvements in chemical energy conversion depend to a large extend on the control of reactions at aqueous interfaces. One focus of RESOLV will be the investigation of the molecular basis of oxygen reduction reactions at liquid/solid interfaces. Achieving a detailed molecular understanding of these processes is of major importance, since these not only determine the performance of fuel cells, but also have an impact on corrosion, on the efficiency of metal-air batteries, and on the performance of photo-electrochemical cells.