Borosilicate-based　glasses　are　the　most　common　sealant　materials　for　solid　oxide　fuel　cells　(SOFCs).　However,　boron　species　vaporizing　from　glass　sealants　poison　and　degrade　the　electrocatalytic　activity　of　cathodes　of　SOFCs.　In　this　study,　we　report　the　development　of　a　new　class　of　glass　sealants　based　on　bismuth　and　zinc　doped　borosilicates　with　significantly　suppressed　boron　volatility.　Doping　Bi　induces　the　[BO3]　→　[BO4]　transition　with　an　increased　binding　energy　of　boron,　while　addition　of　Zn　leads　to　the　formation　of　a　boron-containing　compound,　Sr3B2SiO8,　with　significantly　increased　stability　of　boron　in　the　glass　matrix.　Using　La0.6Sr0.4Co0.2Fe0.8O3　(LSCF)　perovskite　oxide　as　the　cathode　to　assess　the　boron　deposition　and　poisoning,　the　results　indicate　that　the　polarization　performance　of　the　LSCF　cathode　for　the　O2　reduction　reaction　in　the　presence　of　Bi　and　Zn　doped　glass　is　very　stable　with　a　negligible　change　in　the　microstructure　of　the　electrodes.　In　contrast,　in　the　case　of　conventional　borosilicate　glass,　boron　preferentially　deposits　in　the　electrode/electrolyte　region　under　cathodic　polarization,　forming　primarily　LaBO3,　disintegrating　the　perovskite　structure　and　significantly　degrading　the　electrochemical　activity　of　the　LSCF　cathodes.　Doping　Bi　or　Zn　remarkably　reduces　the　boron　volatility　of　the　glass,　thus　effectively　inhibiting　the　poisoning　of　boron　species　on　the　microstructure　and　electrocatalytic　activity　of　SOFC　cathodes　such　as　LSCF.　The　present　results　demonstrate　for　the　first　time　that　the　Bi　and　Zn　doping　is　the　most　effective　strategy　to　minimize　the　boron　poisoning　from　the　source　by　suppressing　the　boron　vaporization　of　borosilicate-based　glass　sealant　materials.　This　journal　is　©　the　Partner　Organisations　2014.