Fresnel zone plates with minimum zone widths down to 50 nm were fabricated by electron‐beam lithography, tested, and used in the scanning x‐ray microscope at the Brookhaven National Synchrotron Light Source. The zone plates consist of gold rings on a silicon nitride window. Characterization of the zone plates included efficiency and resolution measurements in the first order focus. Spatial resolution down to 75 nm was measured. The best zone plates showed negligible astigmatism, and a first order efficiency in excess of 5% has been achieved. A new method for development monitoring during the fabrication procedure using an optical microscope with polarized light and crossed analyzer was introduced. For the inspection of the fabrication accuracy and, in particular, for ellipticity, a moiré pattern technique was employed. Using these zone plates as objective lenses, x‐ray images of biological specimens were obtained with 70 nm resolution.