Thulium-doped Lu2O3 nanocrystals with Ia (3) over bar cubic phase and mean grain size of 17 nm were synthesized by using a modified Pechini method. Their spectroscopic properties have been characterized by Raman, optical absorption, photoluminescence and cathodoluminescence spectroscopies at low and room temperatures, with emphasis on blue and infrared emissions. The reduction of the crystal size induces an increase of the optical line widths and new non-radiative de-excitation paths ascribed to a surface effect