Polycrystalline pyridinium perrhenate has been studied over a wide range of temperatures by differential thermal analysis, differential scanning calorimetry, proton NMR spectra and relaxation, and dielectric permittivity measurements. Two solid–solid phase transitions at 250 and 333 K have been revealed and the pyridinium cation reorientations characterized. The higher transition appears to be the Curie point of a new ferroelectric compound.