LaB6 nanoparticles have been prepared successfully by a stirred bead milling process. The anionic surfactant dodecylbenzenesulfonic acid was found to be suitable for the grinding and dispersion of LaB6 powders, but cationic surfactant polyethyleneimine and nonionic surfactant polyethylene glycol could not yield a stable dispersion. Three kinds of grinding beads with the diameters of 50, 100, and 200 mu m all could reduce the mean hydrodynamic diameter of LaB6 powders to about 100 nm. However, although the grinding rate was slower, using the smaller grinding beads with a diameter of 50 mu m could yield a dispersion of LaB6 nanoparticles with more uniform size. The resulting LaB6 nanoparticles were confirmed to remain a cubic structure and the contaminant from ZrO2 beads was below 5 wt%. Furthermore, the LaB6 nanoparticles exhibited a characteristic absorption around 1000 nm and possessed an excellent near infrared (NIR) photothermal conversion property better than Au nanoshells. Because they were relatively cheap and easy-to-preparation than Au nanorods or nanoshells, the LaB6 nanoparticles could be used as a novel and effective NIR photothermal conversion material and might find great potential in the biomedical application. (C) 2011 Elsevier B.V. All rights reserved.