Blowing bubbles: Hydrogen evolution by proton reduction with [(C 5Me5)2Fe] occurs at a soft interface between water and 1,2-dichloroethane (DCE). The reaction proceeds by proton transfer assisted by [(C5Me5)2Fe] across the water-DCE interface with subsequent proton reduction in DCE. The interface essentially acts as a proton pump, allowing hydrogen evolution by directly using the aqueous proton. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.