Results of thermo-optical investigations for lead germanate (Pb5Ge3O11), potassium dihydrogen phosphate (KH2PO4) ferroelectric crystals, and lead titanate (PbTiO3) thin films expitaxially deposited on (001) SrTiO3 substrate are presented in this article. The measurements were performed using VUV spectroscopic ellipsometry with synchrotron radiation in the temperature range comprising structural phase transitions (PTs) in the materials under study. Distinct anomalies in the temperature dependencies of complex dielectric permittivity and the intensity of reflected synchrotron light are found in the vicinity of ferroelectric-to-paraelectric PT point and discussed. Different temperature points of the characteristic anomalies at the PT of the real and imaginary components of the pseudo-dielectric function are observed for Pb5Ge3O11 and KH2PO4. It is crucial that anomalies in the measured temperature dependences for PbTiO3 thin films on SrTiO3 substrates are observed at the temperature near 105 K, corresponding to the PT in the SrTiO3 single crystal.