A process for preparing optically active alkanols of the formula I in which n is an integer from 0 to 5; Cyc is an optionally substituted, mono- or polynuclear, saturated or unsaturated, carbocyclic or heterocyclic ring, and R1 is halogen, SH, OH, NO2, NR2R3 or NR2R3R4+X−, with R2, R3 and R4 independently of one another being hydrogen or a lower alkyl or lower alkoxy radical and X− being a counterion, which process comprises incubating in a medium comprising alkanone of the formula II  in which n, Cyc and R1 are as defined above, an enzyme having a polypeptide sequence (i) SEQ ID NO: 1 or (ii) in which, compared to SEQ ID NO:1, up to 25% of the amino acid radicals have been altered by deletion, insertion, substitution or a combination thereof and which retains at least 50% of the enzymic activity of SEQ ID NO:1, with the compound of the formula II being enzymically reduced to give the compound of the formula I, and isolating the product formed.