[en] Neutron diffraction analysis was used to study the structure and phase composition of uranium oxocarbonitrides, depending on synthesis conditions. Structure parameters and solubility limits of components in U-C-N-O system phases at room temperature were determined. It was revealed, that oxygen and nitrogen solubility in uranium dicarbide, as well as nitrogen and carbon solubility in uranium dioxide were practically absent. Relative phase content in oxocarbonitrides at room temperature depended sufficiently on nitrogen concentration in the lattice of UC_1-x-yN_xO_y solid solution