A　sonochemical　method　was　developed　for　the　fabrication　of　novel　square-shaped　TiO2　nanocrystals　doped　with　different　F　contents.　The　prepared　samples　were　characterized　by　some　physicochemical　characterizations　like　X-ray　diffraction　(XRD).　N-2　physical　adsorption,　X-ray　photoelectron　spectroscopy　(XPS),　Fourier　transform　infrared　spectrum　(FT-IR),　scanning　electron　microscopy　(SEM),　transmission　electron　microscopy　(TEM),　photoluminescence　(PL)　spectroscopy　and　UV-vis　diffuse　reflectance　spectra　(DRS).　Phenol,　as　a　hazardous　chemical　in　water,　was　chosen　to　evaluate　the　photocatalytic　degradation　performance　of　the　prepared　TiO2　nanocrystals　under　UV　light　irradiation.　Results　show　that　under　ultrasonic　irradiation　conditions.　F　can　easily　be　doped　into　TiO2　and　the　obtained　pure　and　F　doped　TiO2　nanocrystals　show　mesoporous　structures　which　were　formed　by　the　role　of　ultrasound-induced　aggregation.　Moreover,　the　doping　of　optimal　content　of　F　(1.3　mol%)　gives　5.3　times　increase　in　the　phenol　degradation　rate.　The　high　photocatalytic　degradation　activity　of　the　doped　TiO2　could　be　attributed　to　the　factor　that　F　doping　increases　the　surface　hydroxyl　groups　over　TiO2　and　effectively　reduces　the　recombination　rate　of　photo-generated　electron/hole　pairs,　then　producing　more　(OH)-O-center　dot　radicals　to　decompose　the　phenol　molecules.　(c)　2012　Elsevier　B.V.　All　rights　reserved.