A　series　of　poly(benzimidazole　sulfone)s　(PBSs)　and　poly(benzimidazole　ketone)s　(PBKs)　containing　5,6-dimethoxy-1,3-dihydro-2H-benzo[d]imidazol-2-one　(MBIO)　have　been　synthesized　by　C-N/C-O　coupling　with　different　percentages　of　three　other　diphenol　monomers　under　similar　conditions.　The　structure　of　PBS-MBs　and　PBK-MBs　was　confirmed　using　H-1　NMR　and　Fourier　transform　infrared　spectroscopies,　and　X-ray　diffraction　data　revealed　that　all　the　polymers　are　in　an　amorphous　state.　Due　to　the　introduction　of　methoxy,　the　polymers　were　more　soluble　in　common　aprotic　polar　solvents.　The　intrinsic　viscosity　of　the　synthesized　polymers　was　measured　with　an　Ubbelohde　viscometer,　ranging　from　0.38　to　1.35　dL　g(-1).　The　MBIO-based　polymers　have　a　remarkably　good　thermal　stability　with　a　high　glass　transition　temperature　of　up　to　305.1　?.　Furthermore,　the　wavelength　of　maximum　fluorescence　emission　from　homopolymers　is　around　414　nm　with　emission　of　blue　light　in　N-methyl-2-pyrrolidone　solution　(1　mg　L-1)　and　around　530　nm　in　films.　They　also　showed　low　dielectric　constants　(kappa　=　2.60-3.10　at　1　MHz)　and　low　water　absorption　(0.22-0.58%).　It　was　encouraging　to　discover　that　these　polymers　have　potential　utility　for　the　microelectronics　industry,　in　which　good　solubility　facilitates　processing　and　molding,　excellent　thermal　stability　allows　devices　to　be　used　under　harsh　conditions,　low　water　absorption　prevents　device　expansion　and　shrinkage　and　low　dielectric　constant　is　desired　to　prevent　crosstalk　between　conducting　paths.　(c)　2023　Society　of　Industrial　Chemistry.