[en] Magnetic susceptibility measurements show an antiferromagnetic ordering phenomenon for K₂UBr₅. There is a broad maximum in the χ versus T curve at about 10 K. Aiming at the determination of the magnetic structure of K₂UBr₅, powder neutron diffraction investigations were performed. The nuclear structure of K₂UBr₅(K₂PrCl₅ type of structure) was refined at 15 K in the paramagnetic state. The magnetic structure, which was determined from a measurement at 1.5 K in the magnetically ordered state, belongs to the Shubnikov space group Pn'm'a' with k = 0. In the uranium chains along [010] there is an antiferromagnetic ordering of the magnetic moments with components in the (010) plane only. The magnetic moments of neighboring chains are perpendicular to each other within the error limit. Each U³⁺ has an ordered magnetic moment of 2.31(4) μ_B. According to the temperature dependence of the intensity of the 010 and 111 magnetic peaks the Neel temperature is 2.8(3) K. Presumably, there is a short-range magnetic ordering along the [UBr₃Br_4/2]^2- chains giving rise to the maximum of χ at T = 10 K, followed by long-range (three-dimensional) ordering at 2.8 K. 19 refs., 5 figs., 3 tabs