A basic ionic liquid, 1-butyl-3-methyl imidazolium hydroxide ([bmim]OH), efficiently promotes a one-pot, three-component condensation of aromatic aldehydes, malononitrile or ethyl cyanoacetate, and 2-hydroxy-1,4-naphthoquinone to produce 4-aryl-5,10-dihydro-4H-benzo[g]chromene-5,10-dione derivatives in high yields at room temperature. This reaction does not involve any hazardous organic solvent and toxic catalyst. The ionic liquid is recovered and recycled for subsequent reactions. Moreover, this protocol has the advantages of easy work-up, short reaction time, high yields, and environmentally benign procedure compared with the reported methods. J. Heterocyclic Chem., (2011).