A supported copper sulphate catalyst which may be used as a hydration catalyst in the production of an unsaturated alcohol by reacting water with an unsaturated ether, in the vapour phase (see Group IV (b)) may be prepared by dissolving copper sulphate in water to make a volume of solution just sufficient to wet the granular carrier thoroughly, mixing the carrier with the solution and drying in air at about 200 DEG C. Sodium sulphate or potassium sulphate may be added as promoters and the catalyst may be acid-treated or caustic alkali-treated, e.g. by soaking the dried supported catalyst in sodium hydroxide solution. An unsupported copper sulphate catalyst of neutral reaction is prepared by adding sodium hydroxide solution to copper sulphate solution, drying and granulating. A copper sulphate on activated alumina catalyst may be regenerated by oxidation with air at about 475 DEG to 550 DEG C. In an example, an alumina catalyst is prepared by boiling activated alumina in sodium hydroxide solution and then digesting in concentrated aluminium sulphate solution. U.S.A. Specifications 1,868,869, 1,949,344 and 2,015,593 are referred to.ALSO:An unsaturated alcohol is produced from an unsaturated ether thereof by reacting water with an unsaturated ether containing an unsaturated linkage between two carbon atoms of aliphatic character, one of which is directly linked to a saturated carbon atom which in turn is directly linked to the ether oxygen atom, the reaction being effective in the vapour phase in the presence of a hydration catalyst. Specified unsaturated ethers are allyl methyl ether, methallyl ethyl ether, crotyl methyl ether, allyl vinyl ether, methallyl isopropyl ether, tiglyl phenyl ether, cinnamyl butyl ether, allyl cyclohexyl ether, 3-chloro-2-propenyl ethyl ether, propargyl methyl ethel, and their homologues; allyl 3-butenyl ether, methallyl 3-pentenyl ether, crotyl 4-cyclohexenyl ether, allyl methallyl ether, allyl cinnamyl ether, methallyl tiglyl ether, allyl crotyl ether, 3-chloro-2-propenyl methallyl ether, allyl propargyl ether and their homologues; diallyl ether, di-(methallyl) or dicrotyl, ditiglyl, dicinnamyl, di-(3-chloro-2-butenyl), di-(ethallyl), di-(2-cyclopentenyl), di-(3-chloro-2-propenyl), di - (2 - methyl - 2 - hexenyl), di - (2 - methyl - 2 - pentenyl) and di-(2-cyclohexenyl) ethers and their homologues. The reaction temperature is preferably between 180 DEG and 300 DEG C. and atmospheric, reduced or elevated pressures may be employed. Solid hydration catalysts which may be employed include copper sulphate, aluminium sulphate, ferrous sulphate, cobaltous sulphate, nickelous sulphate, aluminium phosphate, cadmium metaphosphate and activated alumina or mixtures thereof. The catalyst may be supported on a carrier, e.g. alumina, thoria, diatomaceous earth, porous carborundum, silicon carbide porous aggregates or silica gel and particularly adsorptive or activated aluminas including alumina alpha trihydrate known as gibbsite or hydrargillite, the alumina beta trihydrate bayerite and the alumina alpha monohydrate bochmite, gamma alumina, gelatinous aluminium hydroxide, bauxite, and the adsorptive alumina prepared by dehydration of alumina trihydrate crystallised from alkali aluminate solutions. A substance such as sodium sulphate or potassium sulphate may be added to help promote the catalyst which may be acid treated or caustic alkali-treated. It is preferred to employ a space velocity of between 0.1 and 10.0 liquid volumes of ether per volume of catalyst per hour. Examples describe the production of allyl alcohol by reacting diallyl ether and steam in the presence, respectively, of the following hydration catalysts: copper sulphate on activated alumina; copper sulphate and diatomaceous earth; copper sulphate treated with sodium hydroxide solution and then dried and granulated; activated alumina; a catalyst prepared by boiling activated alumina in sodium hydroxide solution and then digesting in concentrated aluminium sulphate solution; pelleted aluminium phosphate prepared as in U.S.A. Specification 1,949,344 by adding an aqueous solution of ammonium acid phosphate to an aqueous solution of aluminium nitrate, making the solution alkaline with ammonia and drying and pelleting the precipitated aluminium phosphate with a minor amount of the material "Hyflo Supercel" (Registered Trade Mark) added; other examples describe the production of methallyl alcohol from di-(methallyl) ether and steam using copper sulphate on activated alumina; crotyl alcohol from dicrotyl ether and steam using the same catalyst, and allyl alcohol and methallyl alcohol by reacting allyl methallyl ether and steam over copper sulphate. U.S.A. Specifications 1,868,869 and 2,015,593 also are referred to. The Specification as open to inspection under Sect. 91 also specifies the following unsaturated ethers as starting materials: 3-butenyl methyl ether, 3-pentenyl propyl ether, 3-hexenyl amyl ether, 4-hexenyl ethyl ether, 3-cyclohexenyl vinyl ether, 5-hexenyl isopropenyl ether, di-(3-butenyl) ether, di-(3-pentenyl) p ether, di-(4-hexenyl) ether and di-(4-cyclohexenyl) ether and an example is given for the production of 1-buten-4-ol by the reaction of di-(3-butenyl) ether and steam in the presence of copper sulphate treated with sodium hydroxide solution and then dried and pelleted. This subject-matter does not appear in the Specification as accepted.