An　acid　photocatalyst　TiO2,　modified　with　H2SO　4,　is　prepared　and　used　to　decontaminate　Chemical　Warfare　Agents　(CWAs)　simulants　2-CEES　(2-chloroethyl　ethyl　sulfide)　and　DMMP　(dimethyl　methylphosphonate)　in　vapor　phase.　Compared　with　the　unmodified　pure　TiO　2　photocatalyst,　the　adsorption　capacity　on　the　sulfated　photocatalyst　increases　by　50%,　and　the　conversion　for　2-CEES　increases　more　than　20%.　It　is　found　that　the　durability　for　decontaminating　DMMP　is　delayed　by　200　min　with　the　modified　photocatalyst.　The　surface　characteristics　of　the　photocatalysts　are　analyzed　by　XPS　and　FT-IR.　The　results　show　that　more　Lewis　and　Bronsted　acid　sites,　considered　to　be　responsible　for　improving　the　reactivity　performance　of　photocatalysts,　are　formed　on　the　sulfated　TiO　2.　©　2007　Springer　Science+Business　Media,　LLC.