Iron availability affects oceanic primary productivity and the strength of the biological carbon pump. However, the mechanism of iron solubility in hypersaline environments is poorly understood. In this work, we investigated the extremely halophilic archaeon Haloferax volcanii to reduce ferrihydrite under 25% salinity, aiming to elucidate its energy metabolism associated with extracellular electron transfer (EET). Ferrihydrite reduction by H. volcanii reached a plateau around the e