Mercury,　a　highly　persistent　and　toxic　substance,　seriously　threatens　the　human　health　and　the　environment.　As　an　environmental　friend　solvent,　ionic　liquids　(ILs)　have　been　used　as　replacements　for　conventional　organic　solvents　in　various　separation　processes.　But　there　are　still　some　technical　aspects　that　need　to　be　addressed　before　ILs　can　be　practically　applied　to　remove　Hg(II)　from　water.　The　first　and　most　important　issue　is　the　recovery　and　recycling　of　ILs　without　significant　loss　to　make　the　process　economically　viable　and　reduce　their　potential　environmental　burden.　In　this　study,　a　novel　approach　for　removal　of　Hg(II)　from　water　was　developed　via　1-octyl-3-methylimidazolium　hexafluorophosphate　([C8MIM]PF6).　Hg(II)　was　extracted　into　[C8MIM]PF6　and　then　reduced　into　Hg(0)　with　formic　acid.　Extraction　and　reduction　conditions　were　optimized.　Because　the　extraction　efficiency　of　Hg(II)　into　the　pristine　[C8MIM]PF6　was　limited,　0.4%　(V/V)　1-methylimidazole　was　added　as　complex　agent　of　Hg(II)　into　[C8MIM]PF6　to　enhance　the　extraction　efficiency.　Under　a　phase　ratio　of　[C8MIM]PF6　to　water　of　1:　50,　almost　100%　of　the　Hg(II)　in　water　phase　(1　mg/L)　was　extracted　into　the　[C8MIM]PF6　phase　after　shaking　for　2　h　at　220　r/min　and　50　degrees　C.　Afterwards,　Hg(II)　concentrated　in　the　IL　was　reduced　to　Hg(0)　by　formic　acid　under　the　heating　condition,　and　then　the　[C8MIM]PF6　was　isolated　for　the　purpose　of　recycling　the　IL.　The　Hg(II)　in　[C8MIM]PF6　was　reduced　to　Hg(0)　using　40%　(V/V)　formic　acid　at　50　degrees　C.　Under　a　phase　ratio　of　40%　(V/V)　formic　acid　to　[C8MIM]PF6　of　4　:　1,　about　60%similar　to　70%　of　Hg(II)　was　reduced　to　Hg(0)　in　20　min.　The　formed　Hg(0)　in　the　mixture　was　removed　after　centrifugation,　and　the　[C8MIM]PF6　was　collected　and　recycled.　The　extraction　efficiency　for　Hg(II)　in　water　was　ca.　83%　in　the　initial　two　runs,　and　then　increased　to　91%similar　to　98%　in　the　following　7　runs　by　the　attribution　of　the　formic　acid　which　is　residues　in　the　IL　phase　and　enhances　extraction　efficiency.