In this work we will present the results of spectroscopic ellipsometry measurements (SE) for determination of the Ge concentration (atomic percent) and thickness of relaxed epitaxial SiGe films (on Si) with thicknesses in the range of 900-2500 A for films with 1-35 atomic percent Ge. The Ge concentration is found by measuring the peak value of the real part of the refractive index (RI) which is correlated with Rutherford backscattering (RBS) measurements of atomic percent of SiGe. Conventional tools such as FTIR are not sufficient for accurate measurement of the thickness of SiGe films, which can be thinner than 1000 Angstrom. Also, previously there have been no in-line tools in production use for measuring the Ge concentration in SiGe films.