The spectra of spontaneous and stimulated luminescence of Lu(2)O(3) : Eu (7 at %) nanopowders at different optical pumping intensities have been investigated. The obtained results-changes in the shape of the red luminescence spectra and in the lifetime of the (5)D(0) excited state of Eu(3+) ions-indicate the onset of superluminescence with an increase in the excitation power. It has been found that an increase in the optical pumping intensity leads to a decrease in the luminescence decay time of the Lu(2)O(3) : Eu (7 at %) phosphor in the stimulated luminescence regime and to an increase in the quantum efficiency of red luminescence with a maximum at 611 nm.