Structural changes during thermally induced polymerization of the dipped thin films prepared from TMSPM, zirconium n- tetrapropoxide and methacrylate acid were investigated using near- and mid-IR spectroscopy. In the mid-IR spectra, the intensity of the band due to C equals C was decreased by the heat-treatment at 160 degrees C. The intensity of the band due to C equals O in the polymerized methacrylate, was increased. In the near-IR spectra, the intensities of a band due to the first overtone of fundamental (nu) as(CH2equals) and a combination changes show that heat-treatment of the films at 160 degrees C leads to depletion of C equals C bonds, indicating that polymerization has occurred of TMSPM and methacrylic acid. However, in the mid-IR spectra, the intensity of the band at around 3500 cm-1, due to O- H bonds, increased with the progress of polymerization of vinyl groups. Near-IR spectra of the dipped thin films showed that this increase in intensity of the O-H band is due to the increase of monomeric water molecules hydrogen bonded to silanols. This indicates that polymerized samples are more hydrophilic than unpolymerized ones. The refractive index of the dipped films, measured with a prism coupling method, increased from 1.508 to 1.516 with the polymerization for composition Zr/(Zr + Si) of 0.2.