Refined crystal structure parameters for PtCoO2, PdCoO2, CuFeO2 (delafossite), and AgFeO2 help to explain the high electrical conductivity of PtCoO2 and PdCoO2 and support the assignment of valence states for each compound. The coordination polyhedron for Pt and Pd is a hexagonal bipyramid with oxygen atoms at the apices and either Pt or Pd in the equatorial positions. The conductivity and short Pt-Pt (Pd-Pd) distances indicate strong metal-metal interactions. The relatively longer Cu-Cu and Ag-Ag distances are consistent with the semiconducting behavior of CuFeO2 and AgFeO2. The refinement results show that atom parameters for other similar phases such as PdRhO2 can be reliably determined using only the Shannon and Prewitt effective ionic radii and the unit cells of these phases