Crystalline PrB6 nanoparticles with the sizes ranging from 100 similar to 300 am were synthesized by a solid-state reaction of Pr6O11/PrCI3 and NaBH4 in the temperature range of 1100 similar to 1200 degrees C. The crystal structure, component and morphology of the PrB6 nanoparticles were characterized by using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results show that the particles crystallize in the CsCl structure type. The selected-area electron diffraction patterns reveal the particles have single-crystalline nature. XANES study shows that the Pr atoms in the PrB6 particles are in trivalent state even if the Pr atoms possess the mixed valence state in the raw material Pr6O11. (C) 2015 Elsevier B.V. All rights reserved.