Die Is-Alder reaction of cyclopentadiene with Me(2) maleate was carried out at 25 C in many ionic liqs. optionally in presence of Lewis acids. The H bond donating groups (proton on heteroatom, hydroxyl functionalized alkyl group) on the cation and weak H bond acceptor capacity of the anions accelerated the reaction and increased the endo:exo stereoselectivity in the absence of Lewis acids. The ionic liqs. with alkylating cations and low viscosity were most efficient. In the ionic liq./Lewis acid systems, the reaction rate and endo:exo stereoselectivity increased significantly. Lewis acids activity was mainly dependent on the ionic lig. anion. The (F(3)CSO(2))(2)NH, PF(6), (F(5)C(2))(3)PF(3) and F(3)CSO(3) anions were recommended. The ionic figs. with high thermal and hydrolytic stability were preferred in view of both the activity of Lewis acids and a recycling.