A growing number of X-ray sources based on the free-electron laser (XFEL) 
principle are presently under construction or have recently started operation. 
The intense, ultrashort pulses of these sources will enable new insights in many 
different fields of science. A key problem is to provide x-ray optical elements 
capable of collecting the largest possible fraction of the radiation and to 
focus into the smallest possible focus. As a key step towards this goal, we 
demonstrate here the first nanofocusing of hard XFEL pulses. We developed 
diamond based Fresnel zone plates capable of withstanding the full beam of the 
world's most powerful x-ray laser. Using an imprint technique, we measured the 
focal spot size, which was limited to 320 nm FWHM by the spectral band width of 
the source. A peak power density in the focal spot of 4×10(17)W/cm(2) was 
obtained at 70 fs pulse length.