Abstract: In the process of production of alcohol by hydration of olefin by reacting water and olefin in a reaction zone, for conversion of the olefin to the alcohol, wherein following the hydration unreacted olefin is separated from the effluent from the reaction zone and recycled to the reaction zone, the improvement which comprises maintaining the concentration of olefin at more than 90 vol.% based on the combined composition of the recycle stream and make-up olefin introduced into the process, as gas. The effluent of the hydration reaction can be separated into an alcohol fraction and a gaseous residue fraction; the residue fraction can be distilled into an overhead fraction and a sump fraction, and the overhead fraction can be employed as the recycle stream. Impurities in the system even though lower boiling than the olefin can be removed in the sump product of the distillation to control the concentration of such impurities in the recycle stream.