Oxygen inhibits hydrogenases, a group of enzymes that are able to produce and split hydrogen. This degradation is fatal for possible biotechnological applications of these enzymes for the production of clean energy. Understanding the mechanisms of this process is hence essential. An international team led by researchers from UCL (UK), CNRS (France) and nanoGUNE/Ikerbasque, have combined theory and experiment to characterize each chemical reaction step that results in the reduction of oxygen by the enzyme. These results are being published this week in the journal Nature Chemistry.