Nanoparticles of metal sulfides (ZnS and CdS) have been successfully synthesized using an ionic liquid 1-n-butyl-3methylimidazolium tetrafluoroborate ([BMIM]BF4) under microwave heating at 100 degreesC for 10 min. The products were characterized by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM).