Alkyl-substituted butenols having the formula (I): R.sup.1--CH.sub.2--CH.dbd.CR.sup.2--CH.sub.2OH (I) wherein R.sup.1 is a saturated or olefinically unsaturated alkyl or cycloalkyl group having from 4 to 16 carbon atoms and wherein R.sup.1 is optionally substituted by an alkyl, cycloalkyl, aryl or alkaryl having up to 12 carbon atoms; R.sup.2 is hydrogen or an alkyl group having from 1 to about 6 carbon atoms are produced by a process which comprises: (1) reacting an aldehyde of the formula (II): R.sup.1--CH.sub.2--CHO (II) wherein R.sup.1 has the same meaning as in formula (I), with the corresponding lower aldehyde to form an unsaturated aldehyde in an inert organic solvent; (2) continuously contacting an optionally calcined copper/zinc catalyst with the unsaturated aldehyde under isothermal conditions at temperatures of from about 45 to about 60.degree. C. and under a hydrogen pressure of from 1 to about 300 bar.