Three kinds of chloride fluxes were chosen to assist the preparation of SmBO3 by the solid state reaction method. Synthesis temperature and optical properties of SmBO3 were investigated by the optimization of chloride fluxes. Phase compositions and light reflective properties were characterized by XRD and UV3600, respectively. Single phase SmBO3 powders could be obtained with 15 wt% NH4Cl or 10 wt% MgCl2 at 800 degrees C and they exhibited good optical absorption properties at 1.06 mu m near infrared light with the reflectivity of about 0.6%. For ZnCl2 flux, only 5 wt% could produce single phase SmBO3 at 700 degrees C. Furthermore, the effect mechanism of three kinds of chloride fluxes was discussed. (C) 2015 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.