Two　new　3D　tubular　polyoxoniobate　frameworks,　[Cu(en)2]2{[Cu(en)2]2K4Ba2(H2O)13(SiNb18O54)}2.3en.52H2O　(1)　and　H6[Cu(en)2]2{[Cu(en)2]2NaBa2(H2O)7(SiNb18O54)}2.3en.50H2O　(2)　(en　=　ethylenediamine)　have　been　synthesized　by　hydrothermal　reactions.　Interestingly,　their　frameworks　both　consist　of　rare　inorganic-organic　hybrid　polyoxoniobate　nanotubes　and　helical　heterometallic　Ba2K4O13　/　Ba2NaO7　cluster　chains.　The　nanotubes　are　both　built　from　{SiNb18O54}　clusters　and　copper-organic　complexes.　Compounds　1　and　2　present　excellent　proton　conduction　properties.