A process for the preparation of an optically active carbonyl compound by asymmetric hydrogenation of a prochiral α,β-unsaturated carbonyl compound with hydrogen in the presence of at least one optically active transition metal catalyst that is soluble in the reaction mixture and which has rhodium as catalytically active transition metal and a chiral, bidentate bisphosphine ligand, wherein the reaction mixture during the hydrogenation of the prochiral α,β-unsaturated carbonyl compound additionally comprises at least one compound of the general formula: in which R 1, R 2: are identical or different and are C 6 - to C 10 -aryl which is unsubstituted or carries one or more substituents which are selected from C 1 - to C 6 -alkyl, C 3 - to C 6 -cycloalkyl, C 6 - to C 10 -aryl, C 1 - to C 6 -alkoxy and amino; Z is a group CHR 3 R 4 or aryl which is unsubstituted or carries one or more substituents which are selected from C 1 - to C 6 -alkyl, C 3 - to C 6 -cycloalkyl, C 6 - to C 10 -aryl, C 1 - to C 6 -alkoxy and amino, in which R 3 is C 1 - to C 4 -alkyl, C 1 - to C 4 -alkoxy-C 1 - to C 4 -alkyl, C 3 - to C 6 -cycloalkyl or C 6 - to C 10 -aryl, where one or two nonadjacent CH 2 groups in C 3 - to C 6 -cycloalkyl can also be replaced by an oxygen atom; R 4 is C 1 - to C 4 -alkyl which is unsubstituted or carries a group P(=O)R 4a R 4b, C 1 - to C 4 -alkoxy, C 1 - to C 4 -alkoxy-C 1 - to C 4 -alkyl, C 3 - to C 6 -cycloalkyl or C 6 - to C 10 -aryl, where one or two nonadjacent CH 2 groups in C 3 - to C 6 -cycloalkyl can also be replaced by an oxygen atom, and where C 3 - to C 6 -cycloalkyl and C 6 - to C 10 -aryl are unsubstituted or carry one or more substituents which are selected from C 1 - to C 4 -alkyl, C 1 - to C 4 -alkoxy and amino; or R 3, R 4: together with the carbon atom to which they are bonded, are C 4 - to C 8 -cycloalkyl, in which one or two nonadjacent CH 2 groups in C 3 - to C 6 -cycloalkyl can also be replaced by an oxygen atom and where C 3 - to C 6 -cycloalkyl is unsubstituted or carries one or more substituents which are selected from C 1 - to C 4 -alkyl, C 1 - to C 4 -alkoxy and A-P(=O)R 4a R 4b, where A is a chemical bond or a C 1 - to C 4 -alkylene; and R 4a, R 4b: are identical or different and are phenyl which is unsubstituted or carries one or more substituents which are selected from C 1 - to C 6 -alkyl, C 3 - to C 6 -cycloalkyl, C 6 - to C 10 -aryl, C 1 - to C 6 -alkoxy and amino. R 1, R 2: are identical or different and are C 6 - to C 10 -aryl which is unsubstituted or carries one or more substituents which are selected from C 1 - to C 6 -alkyl, C 3 - to C 6 -cycloalkyl, C 6 - to C 10 -aryl, C 1 - to C 6 -alkoxy and amino; Z is a group CHR 3 R 4 or aryl which is unsubstituted or carries one or more substituents which are selected from C 1 - to C 6 -alkyl, C 3 - to C 6 -cycloalkyl, C 6 - to C 10 -aryl, C 1 - to C 6 -alkoxy and amino, in which R 3 is C 1 - to C 4 -alkyl, C 1 - to C 4 -alkoxy-C 1 - to C 4 -alkyl, C 3 - to C 6 -cycloalkyl or C 6 - to C 10 -aryl, where one or two nonadjacent CH 2 groups in C 3 - to C 6 -cycloalkyl can also be replaced by an oxygen atom; R 4 is C 1 - to C 4 -alkyl which is unsubstituted or carries a group P(=O)R 4a R 4b, C 1 - to C 4 -alkoxy, C 1 - to C 4 -alkoxy-C 1 - to C 4 -alkyl, C 3 - to C 6 -cycloalkyl or C 6 - to C 10 -aryl, where one or two nonadjacent CH 2 groups in C 3 - to C 6 -cycloalkyl can also be replaced by an oxygen atom, and where C 3 - to C 6 -cycloalkyl and C 6 - to C 10 -aryl are unsubstituted or carry one or more substituents which are selected from C 1 - to C 4 -alkyl, C 1 - to C 4 -alkoxy and amino; or R 3, R 4: together with the carbon atom to which they are bonded, are C 4 - to C 8 -cycloalkyl, in which one or two nonadjacent CH 2 groups in C 3 - to C 6 -cycloalkyl can also be replaced by an oxygen atom and where C 3 - to C 6 -cycloalkyl is unsubstituted or carries one or more substituents which are selected from C 1 - to C 4 -alkyl, C 1 - to C 4 -alkoxy and A-P(=O)R 4a R 4b, where A is a chemical bond or a C 1 - to C 4 -alkylene; and R 4a, R 4b: are identical or different and are phenyl which is unsubstituted or carries one or more substituents which are selected from C 1 - to C 6 -alkyl, C 3 - to C 6 -cycloalkyl, C 6 - to C 10 -aryl, C 1 - to C 6 -alkoxy and amino. R 3 is C 1 - to C 4 -alkyl, C 1 - to C 4 -alkoxy-C 1 - to C 4 -alkyl, C 3 - to C 6 -cycloalkyl or C 6 - to C 10 -aryl, where one or two nonadjacent CH 2 groups in C 3 - to C 6 -cycloalkyl can also be replaced by an oxygen atom; R 4 is C 1 - to C 4 -alkyl which is unsubstituted or carries a group P(=O)R 4a R 4b, C 1 - to C 4 -alkoxy, C 1 - to C 4 -alkoxy-C 1 - to C 4 -alkyl, C 3 - to C 6 -cycloalkyl or C 6 - to C 10 -aryl, where one or two nonadjacent CH 2 groups in C 3 - to C 6 -cycloalkyl can also be replaced by an oxygen atom, and where C 3 - to C 6 -cycloalkyl and C 6 - to C 10 -aryl are unsubstituted or carry one or more substituents which are selected from C 1 - to C 4 -alkyl, C 1 - to C 4 -alkoxy and amino; R 3, R 4: together with the carbon atom to which they are bonded, are C 4 - to C 8 -cycloalkyl, in which one or two nonadjacent CH 2 groups in C 3 - to C 6 -cycloalkyl can also be replaced by an oxygen atom and where C 3 - to C 6 -cycloalkyl is unsubstituted or carries one or more substituents which are selected from C 1 - to C 4 -alkyl, C 1 - to C 4 -alkoxy and A-P(=O)R 4a R 4b, R 4a, R 4b: are identical or different and are phenyl which is unsubstituted or carries one or more substituents which are selected from C 1 - to C 6 -alkyl, C 3 - to C 6 -cycloalkyl, C 6 - to C 10 -aryl, C 1 - to C 6 -alkoxy and amino.