Thermally-stimulated depolarization measurements on single-crystal specimens of KOH-doped ice have shown that the crystal structure of ice XI has ferroelectric ordering parallel to its c-axis. The charge-release peak identified with the detransformation of ice XI to ice Ih is produced at the 72 K transition temperature. This temperature is independent of experiment parameters, such as the magnitude of the original polarizing field, the temperature at which the ice had been transformed in this field, and the length of time for which the ice had been subjected to these conditions. The size of the charge release depends on the conditions of transformation but is always smaller than that predicted for full ferroelectric ordering.