The　potential　coexistence　and　interaction　of　bromine　and　polyamide　membranes　during　membrane-based　water　treatment　prompts　us　to　investigate　the　effect　of　bromine　on　membrane　performance.　For　fully　aromatic　polyamide　membrane　NF90　exposed　under　a　mild　bromination　condition　(10　mg/L),　bromine　incorporation　resulted　in　more　negatively　charged　(-13　vs　-25　mV)　and　hydrophobic　(55.2　vs　58.9°)　surfaces　and　narrower　pore　channels　(0.3　vs　0.29　nm).　The　permeabilities　of　water　and　neutral　solutes　were　reduced　by　64　and　69-87%,　respectively,　which　was　attributed　to　the　decreased　effective　pore　radius　and　hydrophilicity.　NaCl　permeability　was　reduced　by　90%　as　a　synergistic　result　of　enhanced　size　exclusion　and　charge　repulsion.　The　further　exposure　(100　and　500　mg/L　bromine)　resulted　in　a　more　hydrophobic　surface　(61.7　and　65.5°)　and　the　minor　further　reduction　for　water　and　solute　permeabilities　(1-9%).　Compared　with　chlorine,　the　different　incorporation　efficiency　and　properties　(e.g.,　atomic　size,　hydrophilicity)　of　bromine　resulted　in　opposite　trends　and/or　different　degrees　for　the　variation　of　physicochemical　properties　and　filtration　performance　of　membranes.　The　bromine　incorporation,　the　shift　and　disappearance　of　three　characteristic　bands,　and　the　increased　O/N　ratio　and　calcium　content　indicated　the　degradation　pathways　of　N-bromination　and　bromination-promoted　hydrolysis　under　mild　bromination　conditions　(480　mg/L·h).　The　further　ring-bromination　occurred　after　severe　bromine　exposure　(4800-24,000　mg/L·h).　The　semi-aromatic　polyamide　membrane　NF270　underwent　a　similar　but　less　significant　deteriorated　filtration　performance　compared　with　NF90,　which　requires　a　different　explanation.　©