Cellulose can be converted to a mixture of ethyl levulinate and levulinic acid by heating with a Brönsted acidic ionic liquid catalyst in aqueous ethanol medium in a one-pot operation under mild conditions. The highest ethyl levulinate yield of 19.0 % was obtained for a reaction carried out at 170 °C for 12 h in water-ethanol medium containing 38.5 % water and using 1-(1-propylsulfonic)-3-methylimidazolium chloride as the catalyst. The levulinic acid yields continue to increase with increasing water content up to about 54 % water in aqueous ethanol for reactions carried out at 150 °C for 48 h, and the highest levulinic acid yield was 23.7 %. The acidic, ionic liquid catalyst used can be efficiently recovered (96 %) from the water phase with negligible contamination, and the stability of the catalyst was confirmed by comparison of the 1H NMR spectrum of the recovered catalyst with fresh catalyst.