The structural transition of monoclinic GdOOH nanorods was studied by using a diamond anvil cell at room temperature with the probe of Eu3+ ion luminescence under pressures up to 21.4 GPa. The changes of luminescence spectra indicated that a pressure-induced phase transition from the monoclinic phase to the high pressure tetragonal phase occurs at 10.7 GPa for GdOOH nanorods, and the monoclinic GdOOH nanorods are gradually transformed into the tetragonal phase with increasing pressure. After releasing of pressure to the ambient, the high pressure tetragonal phase is retained, and the phase transition of GdOOH nanorods is irreversible. (C) 2014 Elsevier B.V. All rights reserved.