We have recently discovered a series of carbene iridium complexes that are highly active in water oxidation catalysis (Angew. Chem. Int. Ed. 2010, 49, 9765, see also picture). As the water oxidation half-cycle is the demanding (and thus far prohibitive) step when splitting water to oxygen and hydrogen, these iridium complexes hold great potential for the generation of hydrogen as fuel from renewable, non-fossil sources. A key component for the efficient water oxidation appears to be the mesoionic carbene ligand, which is non-innocent and capable of assisting in proton-coupled electron transfer processes.Within this proof-of-concept project we now aim at evaluating a range of factors that will be pivotal to move this fundamentally interesting reactivity pattern into a prototypical device for energy generation. The principal goal thus consists of establishing the viability and to address technical issues and overall directions for using carbene iridium complexes in energy conversion processes. Clarification of intellectual property rights and deciding on an appropriate patent/licensing strategy constitutes a primary subaim. A specific and critical point to be addressed pertains to the robustness and activity of the catalyst in order to warrant the costs for using a precious metal in energy conversion and storage processes. Optimized catalysts will thus be essential, and will be combined with a photo-absorbing semiconductor as water reduction catalyst to accomplish full water splitting in a single, eventually light-driven device. In parallel, industrial contacts will be sought to identify domains for application of the catalytic device, in which longevity will be among the key criteria.