MIL-53(Fe)　was　synthesized　using　a　＇modulator　approach＇　that　utilizes　acetic　acid　(HAc)　as　an　additive　to　control　the　size　and　morphology　of　the　resulting　crystals.　We　demonstrate　that　after　activation　under　vaccum　at　100　°C,　the　MIL-53(Fe)　functions　well　for　H2S　selective　oxidation.　The　introduction　of　acetic　acid　in　the　presence　of　benzene-1,4-dicarboxylic　acid　(H2BDC)　would　result　in　a　series　of　MIL-53(Fe)　nanocrystals　(denoted　as　MIL-53(Fe)-xH,　x　stands　for　the　volume　of　added　HAc　with　morphology　evoluting　from　irregular　particles　to　short　hexagonal　columns.　The　vacuum　treatment　facilitates　the　removal　of　acetate　groups,　thus　generating　Fe3+　Lewis　acid　sites.　Consequently,　the　resulted　MIL-53(Fe)-xH　exhibits　good　catalytic　activity　(98%　H2S　conversion　and　92%　sulfur　selectivity)　at　moderate　reaction　temperatures　(100–190　°C).　The　MIL-53(Fe)-5H　is　superior　to　the　traditional　iron-based　catalysts,　showing　stable　performance　in　a　test　period　of　55　h.　©　2021　Dalian　Institute　of　Chemical　Physics,　the　Chinese　Academy　of　Sciences