Abstract: The invention concerns a method of forming a thin film electro-optic waveguide. In one embodiment, the method comprises forming a platinum film on a substrate, forming a PLZT film on the platinum film, and forming a PZT film on the PLZT film. The PLZT film has a lower refractive index than the PZT film. The PZT film functions as a waveguide core and the PLZT film functions as an optical buffer layer for optically isolating the PZT film from the platinum film. When the structure is thermally processed, the platinum film promotes the crystallinity in the PLZT film, which in turn promotes crystallinity in the PZT film. The invention is particularly useful for integrating non-silica-based electro-optic materials with silica-based waveguide structures. The invention also concerns an optical waveguide device formed by the method.