Study　on　proton　exchange　membrane　(PEM)　with　the　aim　toward　excellent　battery　performance　of　PEM　for　fuel　cells　has　attracted　increasing　attention.　In　this　work,　nanocellulose　(CNC)　aminated　by　KH792　noted　as　NN　was　prepared.　CNC　or　NN/sulfophenylated　poly(ether　ether　ketone　ketone)　(sPEEKK)　nanocomposite　membrane　(SN)　or　(SNN)　were　produced　by　solution　mixing.　SNN　was　further　coated　with　tetraethyl　orthosilicate　(TEOS)　to　obtain　SNNT.　The　properties　of　sPEEKK,　SN,　SNN,　and　SNNT　membranes　were　thoroughly　investigated.　The　proton　conductivity　of　SN4　was　0.22　S　center　dot　cm(-1)　at　90　degrees　C,　while　a　proton　conductivity　of　0.30　S　center　dot　cm(-1)　was　obtained　for　SNN4,　and　an　even　higher　value　of　0.36　S　center　dot　cm(-1)　at　90　degrees　C　was　obtained　for　the　TEOS-coated　SNN4　(SNN4T).　Meanwhile,　SNN4T　showed　high　thermal　stability,　and　its　T-d5　was　as　high　as　318.2　degrees　C.　Furthermore,　the　composite　membrane　coated　with　TEOS　also　presented　excellent　oxidative　stability.　The　mass　of　SNN2T　after　treated　in　Fenton　agent　for　1　h　at　80　degrees　C　was　still　retained　96.2%,　and　it　was　not　fully　dissolved　until　11　h.　It　was　illustrated　that　aminated　CNC/sPEEKK　nanocomposite　membranes　coated　with　TEOS　is　a　kind　of　promising　materials　as　PEMs　for　fuel　cells.　(c)　2019　Wiley　Periodicals,　Inc.　J.　Polym.　Sci.,　Part　A:　Polym.　Chem.　2019