Significantly enhanced temporal stability of poled electro-optic (E-O) polymers could be achieved by inserting a thin sol–gel derived titanium dioxide (TiO₂) barrier layer in the high electric field poling process. The resulting poled film can retain >90% of its original r₃₃ value (169 pm V⁻¹ at 1310 nm) after being annealed at 85 °C for 500 h. This is significantly higher (∼30%) compared to that obtained without the TiO₂ layer. This barrier approach is also applicable to a variety of dielectric polymers although the degree of enhancement varies. The enhanced temporal stability of E-O polymers is attributed to reduced charge injection/accumulation that improves the stability of screening charges for poled films.