As a highly sensitive method ellipsometry needs standards to access the accuracy in a broad spectral range at different incidence angles. The possibility of using a one dimensional multilayer periodic structure with omnidirectional reflection as an ellipsometric Ψ standard is examined both theoretically and experimentally. The omnidirectional reflection for both fundamental polarizations will give constant Ψ value at any angle of incidence for certain spectral range. The transfer matrix approach is used for the system parameters selection and analysis of the influence of the finite number of periods. Electron beam evaporation technique is used for the fabrication of a system consisting of alternating SiO2/TiO2 layers on a glass substrate. The ellipsometric angles of the multilayer structure are measured using spectroscopic photometric ellipsometer in a spectral range from 410 to 700 nm at different angles of incidence and the experimental results are compared with theoretical predictions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)