FeOOH　has　been　explored　as　a　promising　adsorbent　for　low-temperature　H2S　adsorption.　However,　the　nature　of　the　active　sites　toward　the　desulfurization　has　remained　elusive.　Here,　a　series　of　gamma-FeOOH　is　prepared　with　well-defined　lath-like　and　rod-like　shapes　by　adjusting　the　pH　value　of　the　reaction　system.　The　two　shapes　of　gamma-FeOOH　have　identical　bulk　structures　but　expose　different　distributions　of　surface　OH　groups,　namely　singly　(　FeOH,　-OH),　doubly　(　Fe2OH,　mu-OH),　and　triply　coordinated　(　Fe3OH,　mu(3)-OH)　hydroxyls,　allowing　us　to　investigate　the　geometrical-site-dependent　desulfurization　activity　of　gamma-FeOOH　at　molecular-scale　level.　Following　a　thorough　analysis　by　X-ray　diffraction　(XRD),　transmission　electron　microscope　(TEM),　X-ray　photoelectron　spectroscopy　(XPS),　and　in　situ　Fourier　transform　infrared　spectroscopy　(In　situ　FT-IR),　we　demonstrate　that　singly　hydroxyl　(　FeOH,　-OH)　site　is　responsible　for　H2S　adsorption,　which　acts　as　the　active　site　for　low-temperature　desulfurization.　(C)　2017　Elsevier　B.V.　All　rights　reserved.