This is an analytical bond-order potential for the Fe–O system, capable of reproducing the basic properties of wustite as well as the energetics of oxygen impurities in alpha-iron. The potential predicts binding energies of various small oxygen-vacancy clusters in alpha-iron in good agreement with density functional theory results, and is therefore suitable for simulations of oxygen-based defects in iron. The potential is not suitable for simulations of the Fe2O3 and Fe3O4 phases.