Different polyheteroarylenes, such as m-polybenzimidazole, polyphenylene oxide, polymer of intrinsic microporosity (PIM-1) and poly(N-phenylene-benzimidazole) were electrospun to obtain self-supporting polymer nanofiber mats. The mats after heat treatment, which contains stabilization in air at 250-350 degrees C and pyrolysis at 900-1000 degrees C under vacuum, convert into carbon nanofiber paper, a material which is suitable for Pt nanoparticle deposition. The possibility of usage of the obtained carbonized nanocomposites as entire gas diffusion electrodes for high temperature polymer electrolyte membrane fuel cell is shown.