Alkali　and　alkaline-earth　metals　from　fly　ash　have　a　significant　deactivation　effect　on　catalysts　used　for　selective　catalytic　reduction　of　NO　x　by　NH　3　(NH　3　-SCR).　Bromides　are　considered　effective　additives　to　improve　Hg　0　oxidation　on　SCR　catalysts.　In　this　work,　the　effects　of　different　bromides　(NH　4　Br,　NaBr,　KBr,　and　CaBr　2　)　on　a　commercial　V　2　O　5　-WO　3　/TiO　2　catalyst　were　studied.　NO　x　conversion　decreased　significantly　over　the　KBr-poisoned　catalyst　(denoted　as　L-KBr),　while　that　over　NaBr-　and　CaBr　2　-poisoned　catalysts　(denoted　as　L-NaBr　and　L-CaBr,　respectivity)　decreased　to　a　lesser　extent　compared　with　the　fresh　sample.　Poor　N　2　selectivity　was　observed　over　L-NaBr,　L-KBr　and　L-CaBr　catalysts.　The　decrease　in　the　ratio　of　chemisorbed　oxygen　to　total　surface　oxygen　(O　α　/(O　α　+　O　β　+　O　w　)),　reducibility　and　surface　acidity　might　contribute　to　the　poor　activity　and　N　2　selectivity　over　L-KBr　catalyst.　The　increased　O　α　ratio　was　conducive　to　the　enhanced　reducibility　of　L-CaBr.　Combined　with　enhanced　surface　acidity,　this　might　offset　the　negative　effect　of　the　loss　of　active　sites　by　CaBr　2　covering.　The　overoxidation　of　NH　3　and　poor　N　2　selectivity　in　NH　3　oxidation　should　retard　the　SCR　activity　at　high　temperatures　over　L-CaBr　catalyst.　The　increased　basicity　might　contribute　to　increased　NO　x　adsorption　on　L-KBr　and　L-CaBr　catalysts.　A　correlation　between　the　acid-basic　and　redox　properties　of　bromide-poisoned　catalysts　and　their　catalytic　properties　is　established.　＂©　2018,　Dalian　Institute　of　Chemical　Physics,　Chinese　Academy　of　Sciences.　Published　by　Elsevier　B.V.　All　rights　reserved.　＂