This research probes the mechanisms of Zn adsorption on hydrated oxides of iron (HFO and goethite) using XAS. A systematic investigation reveals that Zn2+ upon sorption to HFO retains its hydration shell (N similar to 6 oxygens, R similar to 2.18 Angstrom), irrespective of pH and adsorbate loading. Furthermore, the absence of second-shell contributions in combination with the temperature dependence of the structural parameters confirms outer-sphere adsorption complexes with HFO. In a coprecipitation study, the local coordination environment Aas consistent with Zn adsorption to HFO. On the other hand, Zn2+ strongly adsorbs to goethite forming a tetragonal structure (N similar to 4 oxygens and R similar to 1.97 Angstrom). Evidence of two Fe3+ ions in the second shell at approximately 3.51 Angstrom suggests an inner-sphere adsorption complex with goethite. Results demonstrate that even though the local structures of HFO and goethite are similar, the surface sites available to transition metals like zinc are vastly different. Overall, these spectroscopic analyses are consistent with macroscopic observations.,