Perfluorinated Nafion membranes, neutralized to various extents, were hybridized with titania quasi-networks that were grown in situ via catalyzed sol-gel reactions of an titanium isopropoxide precursor. The formation of Ti-O-Ti groups within the ionomer was verified by FTIR-ATR spectroscopy. EDAX studies confirmed that the extent of propagation of titania quasi-networks into the bulk of the ionomer film increased with ionomer neutralization. Compared to the unmodified control membrane, the hybrid membranes exhibited superior dimensional stability, modulus, stress, and strain at break and gas barrier properties. All hybrid membranes exhibited superior resistance to degradation when subjected to an accelerated stress test in an operating fuel cell environment, as a resultant of the better dimensional stability and gas barrier properties induced through addition of the inorganic titania phase.