A process for preparing cyclic ethers is described. The process involves the reaction of at least one organic compound such as diols or polyol which it has at least one pair of hydroxyl groups separated by 5 or 5 carbon atoms, and which is capable of being converted into an ether linkage, with an organic carbonate in the presence of a base. The base is an alkoxy a carbonate or a hydroxide base or is a mixture of such bases. At least one of the hydroxyl groups of the organic compound is not a tertiary hydroxyl group.