Dielectric lead lanthanum zirconate titanate thin films have been grown on Si(111) substrates by sol-gel processing. The composition of the films is stoichiometric 9/65/35. When annealed at 450 degrees C, the films were found to be amorphous. The refractive index and the extinction coefficient of the films were measured in the spectral range of 1.8-5.5 eV for the first time by photometric spectroellipsometry. The absorption edge is determined at about 3.7 eV.