The proton conductivity of phosphorylated polybenzimidazole PhEPBI-O-PhT has been examined. It has been shown that the acid-free membrane has intrinsic conductivity. A comparative study of the conductive properties of PhEPBI-O-PhT and the nonphosphorylated analogue PBI-O-F1 has been conducted, and it has been found that the presence of grafted phosphonic groups effectively helps to reduce the concentration of phosphoric acid used for doping with a high conductivity being retained. It has been shown that the introduction of phosphonic groups leads to a decrease in hydrogen gas permeability by 23%. The samples were tested in a membrane electrode assembly.