An easily accessible ionic liquid, l-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PFn]) was synthesized, and characterized using 1H and 13C NMR. and MS. The ionic liquid was demonstrated to be an efficient and recyclable solvent for the Sonogashira reaction of iodobenzene and phenylacetylene to form diphenylacetylene as the principal product. It was also found that increasing the length of the alkyl chain in the ionic liquid caused a significant drop in the reaction rate. Using the ionic liquid as the reaction solvent in conjunction with microwave irradiation. the reaction rate was dramatically enhanced, with over 95 percent conversion being achieved within 3 min compared to conversions obtained after 6 hrs under conventional conditions. Furthermore, the ionic liquid - palladium catalyst system could be reused in subsequent reaction without a significant degradation in activity.