The proposed experiment aims to investigate the chemical reactions between iron oxides/hydroxides and water under different oxidation conditions using single-crystal X-ray diffraction (XRD) techniques in laser-heated diamond anvil cells (DACs). We plan to characterize the crystal structures and chemical compositions of the reaction products, with a particular focus on how the presence of strong oxidizers, such as hydrogen peroxide, influences these outcomes. The findings will provide valuable insights into the chemistry and crystal chemistry of the Fe-O-H system, contributing to a deeper understanding of the stability of hydrous phases under lower-mantle conditions.