A　novel,　simple　and　efficient　approach　for　photodegrading　phenol　and　p-chlorophenol,　based　on　BixOy,　was　reported　for　the　first　time.　Monoclinic　Bi2O4　was　prepared　by　the　hydrothermal　treatment　of　NaBiO3　center　dot　2H(2)O.　A　series　of　interesting　phase　transitions　happened　and　various　bismuth　oxides　(Bi4O7,　beta-Bi2O3　and　alpha-Bi2O3)　were　obtained　by　sintering　Bi2O4　at　different　temperatures.　The　results　demonstrated　that　the　Bi2O4　and　Bi4O7　phase　had　strong　abilities　towards　the　oxidative　decomposition　of　phenol　and　p-chlorophenol　and　very　high　rates　of　TOC　removal　were　observed.　The　characterization　by　XRD　and　XPS　revealed　that　Bi4+　in　Bi2O4　and　Bi3.5+　in　Bi4O7　were　reduced　to　Bi3+　during　the　reaction　process.　Singlet　oxygen　(O-1(2))　was　identified　as　the　major　reactive　species　generated　by　Bi2O4　and　Bi4O7　for　the　photodegradation　of　p-chlorophenol　and　phenol.　This　novel　approach　could　be　used　as　a　highly　efficient　and　green　technology　for　treating　wastewaters　contaminated　by　high　concentrations　of　phenol　and　chlorophenols.　(C)　2015　Elsevier　B.V.　All　rights　reserved.