[Fe]-hydrogenase is a newly characterized type of hydrogenase. This enzyme heterolytically splits hydrogen in the presence of a natural substrate. The active site of the enzyme contains a mono-iron complex with intriguing ironacyl ligation. Several groups have recently developed ironacyl complexes as synthetic models of [Fe]-hydrogenase. This Focus Review summarizes the studies of this enzyme and its model compounds, with an emphasis on our own research in this area.