alpha-Ketoglutarate (alpha KG) dependent oxygenases comprise a large superfamily of enzymes that activate O-2 for varied reactions. While most of these enzymes contain a nonheme Fe bound by a His(2)(Asp/Glu) facial triad, a small number of alpha KG-dependent halogenases require only the two His ligands to bind Fe and activate O-2. The enzyme "factor inhibiting HIF" (FIH) contains a His(2)Asp facial triad and selectively hydroxylates polypeptides; however, removal of the Asp ligand in the Asp201 -> Gly variant leads to a highly active enzyme, seemingly without a complete facial triad. Herein, we report on the formation of an Fe-Cl cofactor structure for the Asp201 -> Gly FIH variant using X-ray absorption spectroscopy (XAS), which provides insight into the structure of the His(2)Cl facial triad found in halogenases. The Asp201 -> Gly variant supports anion dependent peptide hydroxylation, demonstrating the requirement for a complete His(2)X facial triad to support O-2 reactivity. Our results indicated that exogenous ligand binding to form a complete His(2)X facial triad was essential for O-2 activation and provides a structural model for the His(2)Cl-bound nonheme Fe found in halogenases.