The efficiency of the polarization scheme based on polycapillary optics and a diamond crystal polarizer was demonstrated. The scheme provides suppression of the background of scattered radiation in measuring X-ray fluorescence spectra. A quasi-parallel X-ray beam with an angular divergence of 4.2 mrad was formed by a microfocus source with a copper anode and polycapillary half-lens. Simultaneous polarization and monochromatization of radiation was obtained with a crystal of natural diamond, which was set at the diffraction reflection (113). The degree of polarization of CuKα1 spectral line and the maximum radiation flux were respectively equal to 99.86% and 5 · 106 photon/s. In the direction orthogonal to the plane of diffraction, the maximum attenuation of the background was up to 19 dB. Copyright © 2017 John Wiley & Sons, Ltd.