AgFeO2 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Fe3+ is bonded to six equivalent O2- atoms to form edge-sharing FeO6 octahedra. All Fe–O bond lengths are 2.06 Å. Ag1+ is bonded in a linear geometry to two equivalent O2- atoms. Both Ag–O bond lengths are 2.12 Å. O2- is bonded to three equivalent Fe3+ and one Ag1+ atom to form a mixture of distorted edge and corner-sharing OFe3Ag tetrahedra.