We propose to use the NIMROD diffraction instrument to produce high-resolution data on the structure of various nanoparticulate iron oxide-hydroxides. Although widely used in a range of applications ¿ including imaging of cancers and the clinical correction of iron deficiency anaemia (IDA) ¿ structural insights into these materials are lacking. Specifically, characterisation of mineral phase and core-coating interactions are required ¿ both from a fundamental and an applied science perspective. We intend to establish the parent mineral phases of relevant materials and examine the impact of surface coatings upon their lattice structures via comparison to phase-pure samples of ferrihydrite and akaganéite. Hydrogen-deuterium substitutions will be employed to enhance structural contrast.