Passive sol-gel materials play an important role in the development of electro-optic(EO) polymer-based modulators, because of their variety of available refractive indices. They can be used to form passive waveguide transitions to minimize coupling loss or as cladding layers for the EO polymer. The demands for these two applications are different. For waveguide transitions the most important factor is the optical loss. Cladding layers should have a relatively high conductivity at elevated temperatures to improve poling efficiency. Both demands are addressed in this study. The synthesis of low loss (down to 0.45 dB/cm) sol-gel materials is shown. Slab waveguides as well as ridge waveguides were fabricated and characterized by liquid prism measurements and cut-back loss measurements, respectively. For use in cladding layers surrounding the EO polymer, materials with higher conductivity were developed. The conductivity of the materials was increased, (3.10-9 S/m) through the use of a silane, which allows in situ formation of proton donating functionalities. All developed materials can be used as solvent free resins, which enables classic photolithography as well as patterning by UV-imprinting. The available refractive index range (at 1.55 μm) is from 1.495 to 1.562.