A combined DSC and high temperature XRD study of the phase transformation reported for the beta-phase solid solution (Bi(2)O3)(1-x) (SrO)(x) was undertaken for the composition Bi1.6Sr0.2O2.6. The DSC and high temperature XRD results were in good agreement. A reversible phase transformation was observed over a narrow temperature range around 650 degrees C, characterized by a large increase in the c lattice parameter, although, both the low and high temperature phases have the same crystal symmetry.