Nanostructured Tb3+-doped Gd2O3 particles have been synthesized from chloride precursors by NaOH addition in a polyol medium. In-situ luminescent spectra have been investigated in order to follow up the process of formation and growth of these particles by varying parameters as the elaboration temperature and the rate of NaOH addition. Contrarily to all the literature related to the "polyol" synthesis, the paper proves that oxide particles can be directly formed at room temperature. These particles are also slightly bigger and organized in nanorods when NaOH is added progressively. Finally, it was found that the influence Of further annealing up to 160 degrees C strongly depends on the NaOH addition rate. While preserving the oxide phase, annealing leads to bigger particles only in the case of a progressive addition of NaOH. (C) 2009 Elsevier Inc. All rights reserved.