A monolithic polycapillary focusing optic was tested in the microbeam x-ray fluorescence system at the Oak Ridge Center for Manufacturing Technology. The optic was designed to cover a wide energy range from 4 keV to 20 keV. The focal spot size of the output beam at 17.4 keV (Mo K&agr;)was measured to be 21&mgr;m full width of half maximum. An average beam intensity of1.5×105photon/s/&mgr;m2was obtained at the focus for Mo K&agr;line using a 12 W microfocus x-ray source. This intensity is about 2400 times over that of a direct beam at 100 mm away from the x-ray source. The small, intense x-ray beam obtained was used to analyze and map the compositions of different elements in industrial samples. ©1997 American Institute of Physics.