In the PTB laboratory at the electron storage ring BESSY flat multilayer mirrors as well as curved multilayer optics are characterized in the soft x-ray region using synchrotron radiation. Precision reflectometry is performed in the spectral range between 5 and 30 nm where the content of higher orders in the monochromatized radiation is below 2%. The existing facilities and current improvements of the instrumentation are described. Examples for spatially resolved measurements of the reflectance of curved multilayer optics are presented.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.