We describe an extensive characterization procedure developed to study multilayers for extended ultraviolet (XUV, 1 A˚≲&lgr;≲1000 A˚) optics. We present results of this procedure applied to sputtered Si/W multilayers designed as normal‐incidence XUV reflectors for ∼200 A˚. Techniques used were low‐angle x‐ray diffraction, Bragg–Brentano and Seemann–Bohlin diffraction, wide‐film Debye–Scherrer (Read) camera, Rutherford backscattering spectroscopy, and transmission electron microscopy. Reflectances at several incidence angles were measured with synchrotron radiation and found to agree very well with reflectance curves calculated without adjustable parameters. The information obtained from the different techniques forms a coherent picture of the structure of these materials.