CsBr:Eu2+ has recently been investigated as a photostimulable x-ray storage phosphor with great potential for application in high-resolution image plates. In a recent paper Hackenschmied etal [J. Appl. Phys. 93, 5109 (2003)] suggested that segregations of CsEuBr3 or Cs4EuBr6 formed within CsBr:Eu2+ during annealing are responsible for an increase in the photostimulated luminescence (PSL) yield. In this work single crystals of CsEuBr3 were prepared by a one step synthesis and identified by x-ray diffraction (XRD) analysis as single phase perovskites. It was concluded that, after preparation, CsEuBr3 degrades in normal atmosphere into at least two phases, one of which is the orthorhombic structure of Cs2EuBr5∙10H2O. The XRD powder diffraction pattern of this compound is very similar to that of the segregations observed within CsBr:Eu2+ and reported by Hackenschmied etal However, the increased PSL yield in CsBr:Eu2+ after annealing cannot be due to the segregations, because the trivalent nature of the europium in the segregations renders them PSL inactive.