Hybrid membranes based on polybenzimidazole and hydrated zirconia doped with phosphoric acid have been synthesized. The effect of synthesis conditions on the properties of the resulting materials has been studied. It has been shown that the modification of the membranes makes it possible to increase their proton conductivity. The introduction of hydrated zirconia decreases the amount of phosphoric acid leached out from the membrane exposed to water vapor. The diffusion permeability of composite membranes in solutions of various salts has been studied. Model tests of some samples under fuel cell operating conditions have been performed.