Diffusion　dialysis　(DD)　has　high　economic　competitiveness　for　acid　recovery;　however,　the　fabrication　of　highly　acid-permeable　and　salt-rejecting　anion　exchange　membranes　(AEMs)　for　DD　is　still　a　grand　challenge.　This　paper　presents　in-situ　cross-linked　porous　AEMs　with　tunable　microstructures　and　high　DD　performance.　The　AEMs　were　fabricated　based　on　chloromethyl　polyethersulfone　substrate　using　N,　N,　N′,　N″,　N″-pentamethyldiethylenetriamine　as　a　bifunctional　agent　for　cross-linking　and　quaternization.　The　prepared　porous　AEMs　showed　significantly　superior　DD　performance　over　conventional　dense　AEMs　due　to　the　high　free　volume　and　cross-linked　networks　within　our　membranes.　The　acid　dialysis　coefficient　(UH+)　and　acid/salt　separation　factor　(S)　of　the　optimal　AEM　were　2.6　and　255.4　times　as　high　as　those　of　the　commercial　DF-120　AEM,　respectively.　Therefore,　our　low-cost,　high-performance　in-situ　cross-linked　porous　AEMs　may　pave　the　way　for　large-scale　acid　recovery　applications.　©　2023