Planar and spherical retarding potential analyzers have been studied as detectors of extreme uv (xuv) radiation between 200 A and 1300 A. Current-voltage diagrams (CVD's) are presented for the photoelectrons emitted from the front and rear surfaces of a semitransparent aluminum cathode for the planar analyzer and from the rear surface of an aluminum cathode for the spherical analyzer. The CVD's obtained in planar geometry for the front and rear surface photoelectrons of aluminum are essentially identical for properly prepared films. The analyzers are compared as tools for a simple method of nonoptical spectrometry. The spherical analyzer is shown to be superior to the planar analyzer in spectral discrimination in the xuv. Calculations applicable to the detection of xuv radiation below 600 A in the presence of unfiltered solar radiation are given.