An efficient and environmentally benign procedure for the synthesis of 1,8-dioxo-octahydroxanthene by condensation reaction between 5,5-dimethyl-1,3-cyclohexanedione (dimedone) and structurally diverse aldehydes using carboxy functionalized ionic liquid under microwave irradiation is described. The methodology provides synergy of ionic liquid and microwave irradiation which offers several advantages such as high yields in shorter reaction time, convenient operation, reusability of catalyst and easy work-up.