Abstract: A magnetic cell with permanent magnets for the synchrotron-radiation diffraction study of small thin-film samples is calculated and the cell design is proposed. The cell induces magnetic fields up to 2 T at a gap between the pole tips of up to 4 mm. The external sizes of the magnetic cell are 110 × 70 × 45 mm, which makes it easy to fix it on a goniometric head. Test experiments are carried out on a Pilatus@SNBL diffractometer at the BM01A station of the Swiss–Norwegian beamlines of the European Synchrotron Radiation Facility.