Nanocrystalline　InOOH　was　synthesized　from　In(NO3)(3)　and　ethylenediamine　via　a　facile　solvothermal　method.　The　obtained　sample　was　characterized　by　X-ray　diffraction　(XRD),　N-2-sorption　(BET　surface　area),　UV-vis　diffuse　reflectance　spectroscopy　(DRS),　transmission　electron　microscopy　(TEM),　high-resolution　transmission　electron　microscopy　(HRTEM),　and　Fourier　transformation　infrared　spectroscopy　(FT-IR).　The　as-prepared　InOOH　showed　photocatalytic　activity　for　benzene　degradation　under　300-nm　UV　irradiations.　Compared　to　P25,　InOOH　showed　comparable　conversion　of　benzene,　higher　mineralization,　and　no　obvious　deactivation　of　InOOH　was　observed　during　the　prolonged　operation.　A　possible　mechanism　of　the　photocatalysis　over　InOOH　was　also　proposed.