An efficient method for the synthesis of N-aryl-5-arylidene-2,4-thiazolidinediones has been developed involving the N-arylation of 5-arylidene-2,4-thiazolidinediones derivatives with diaryliodonium salts in the ionic liquid [bmim]PF6 (1-butyl-3-methylimidazolium hexafluorophosphate).