Tetrahydrofuran (THF) was completely converted to give 1,4-diacetoxybutane selectively at 333 K in the presence of heteropolyacid catalyst. This method is characterized by the reaction of THF with a mixture of acetic acid and acetic anhydride as nucleophiles. This method is applicable also to the acetolysis of other cyclic ethers, such as normally inert 1,4-dioxane, furan and 2-methylfuran. High reaction efficiency is probably due to a cooperative effect by acetyl cations promptly formed from acetic anhydride with heteropolyacid and an excess of acetate anions which could attack the acetylated THF oxocations more predominantly than the attack by THF molecules to form oligomeric products. (C) 2003 Elsevier B.V All rights reserved.