In this investigation, efforts were given to develop carbon-nanofiber-reinforced polybenzimidazol nanocomposite for space application. Processing of polybenzimidazol was carried out by using polybenzimidazol in powder and solution forms. Thermomechanical properties of compression-molded polybenzimidazol, unfilled polyhenzimidazol films, and nanofiber-reinforced polybenzimidazol films were investigated using thermogravimetric analysis, dynamic mechanical analysis, and tensile testing. Thermogravimetric analysis revealed that both compression-molded polybenzimidazol and polybenzimidazol films show high thermal stability. Dynamic mechanical analysis studies depicted that both compression-molded polybenzimidazol and polybenzimidazol neat films exhibited a high storage modulus, even at a temperature of 250 C. Polybenzimidazol nanocomposite films were cast with different loadings of carbon nanofibers from 9.5 to 2 wt % in polymer solution. Addition of carbon nanotibers improved the thermal stability and storage modulus of polybenzimidazol film. Mechanical testing showed that both compression-molded polybenzimidazol and polybenzimidazol films resulted in the highest ultimate tensile strength in comparison to any unfilled polymer. Investigation under scanning electron microscopy confirmed uniform dispersion of carbon nanofibers in polymer solution. Analysis of fractured surfaces revealed that neat polybenzimidazol film exhibited ductile failure and dispersion of carbon nanofibers into the polybenzimidazol, resulting in transformation from ductile to brittle failure.