The present invention provides a process for producing compounds useful as raw materials for various fluororesins in high yields in few steps from inexpensive and readily available starting materials.The following compound (1) and the following compound (2) are reacted to form the following compound (3), then the compound (3) is fluorinated in a liquid phase to form the following compound (4), and the ester bonds in the compound (4) are dissociated to form the compound (5), or the compound (5) and the compound (6). HOCH.sub.2-Q-O--(CH.sub.2).sub.3--OH, (1) CR.sup.BCOX, (2) R.sup.BCOOCH.sub.2-Q-O--(CH.sub.2).sub.3--OCOR.sup.B, (3) R.sup.BFCOOCF.sub.2-Q.sup.F-O--(CF.sub.2).sub.3--OCOR.sup.BF, (4) FCO-Q.sup.F-O--(CF.sub.2).sub.2--COF, (5) R.sup.BFCOF. (6)