The　microstructure,　phase　structure,　ferroelectric　and　dielectric　properties　of　(1-x)(0.94Bi(0.5)Na(0.5)TiO(3-)0.06BaTiO(3))-xNaNbO(3)　(BNT-BT-xNN)　ceramics　were　investigated　as　candidates　for　high-temperature　capacitors　with　a　working　temperature　far　beyond　200　degrees　C.　The　decreased　polar　rhombohedral　phase　shown　in　XRD　and　the　weakened　macroscopical　polarization　in　P-E　test　indicate　that　NN　addition　can　dilute　the　mutual　coupling　of　polar　nanoregions　(PNRs),　which　is　very　conducive　to　flattening　the　curves　of　temperature　dependent　dielectric　permittivity　at　the　expense　of　a　small　reduction　in　dielectric　permittivity　values.　Among　all　manufactured　samples,　those　with　composition　of　x　=　0.10　showed　a　high　permittivity　of　more　than　2700　(1　kHz)　and　energy　storage　density　of　0.61　J/cm(3)　(7　kV/mm)　at　150　degrees　C　with　a　Delta　C/C-150　degrees　C　varying　no　more　than　15%　in　a　wide　temperature　range　of　54　degrees　C-318　degrees　C.　All　of　these　exhibit　wonderful　temperature　stable　dielectric　properties　and　indicated　the　promising　future　of　BNT-BT-xNN　system　as　high-temperature　ceramic　capacitors.　(C)　2017　Elsevier　B.V.　All　rights　reserved.