[en] The organic salt choline chloride exists in two crystalline polymorphs. One (the α form) is extraordinarily sensitive to ionizing radiation, the other (the β form) is not. The present report describes an x-ray diffraction study of the β form. The structure has been found to be highly disordered face centered cubic. A reasonable least-square refinement of the intensity data has been achieved in the centrosymmetric space group Fm3 or Fm3m by use of a molecular model with restrained bond lengths. The results show that in the β form the electronic density due to the choline cation is closely spaced around the N, so that hydrogen bonding to the chloride is unlikely. Comparison with infrared and NMR data indicates that the disordering is dynamic and can be ascribed to rotations of the choline ion around crystallographic symmetry axes. Possible connections of these results with the radiation stability of the β form are discussed