The　ionic　liquid　(1,3-dimethylimidazolium　dimethyl　phosphate　([MMIM][DMP]))　synthesized　by　addition　reaction　was　used　to　modify　a　commercial　reverse　osmosis　(RO)　membrane　thorough　activation　method.　The　activation　promoted　modification　process　was　completed　within　just　6-12　min　under　optimal　condition　of　the　immersion　time　of　4　min,　activation　temperature　of　110　degrees　C　and　activation　time　of　4　min.　The　variation　of　surface　morphologies　and　properties　of　the　RO　membrane　were　characterized　by　SEM,　AFM,　water　contact　angle,　FTIR,　and　the　RO　performance　was　evaluated　by　desalination　of　1000　mg.L-1　NaCl　aqueous　solution.　The　results　showed　that　the　active　layer　of　the　modified　RO　membrane　became　thinner,　smoother,　and　more　hydrophilic　with　increasing　of　activation　temperature.　The　IL　modified　membrane　achieved　water　flux　of　33.7　Lm(-2)　h(-1)　and　rejection　of　93.2%,　showing　62%　higher　water　flux　comparing　to　the　pristine　membrane　and　2.6%　decrease　in　salt　rejection.　Moreover,　the　IL　modified　membrane　showed　an　enhanced　anti-fouling　property　with　95.5%　of　normalized　water　flux　recovery.　This　work　provides　a　facile　and　efficient　way　to　modify　and　improve　separation　performance　and　anti-fouling　property　of　commercial　thin　film　composite　(TFC)　RO　membranes.　(C)　2017　Taiwan　Institute　of　Chemical　Engineers.　Published　by　Elsevier　B.V.　All　rights　reserved.