A process of the asymmetric hydrogenation of a ketal of an unsaturated ketone or an acetal of an unsaturated aldehyde by molecular hydrogen in the presence of at least one chiral iridium complex to yield a ketal or acetal having at least one stereogenic carbon centre; wherein the chiral iridium complex is a chiral iridium complex of formula (III-0) wherein P-Q-N stands for a chelating organic ligand comprising a stereogenic centre or has planar or axial chirality and has a nitrogen and phosphorous atom as binding site to the iridium centre of the complex; Y 1, Y 2, Y 3 and Y 4 independently from each other are hydrogen atoms, C 1-12 -alkyl, C 5-10 -cycloalkyl, or aromatic group; or at least two of them form together at least a two-valent bridged group of at least 2 carbon atoms; and Y ⊖ is an anion, particularly selected from the group consisting of halide, PF 6 -, SbF 6 -, tetra(3,5-bis(trifluoromethyl)phenyl)borate (BAr F -), BF 4 -, perfluorinated sulfonates, preferably F 3 C-SO 3 - or F 9 C 4 -SO 3 -; ClO 4 -, Al(OC 6 F 5) 4 -, Al(OC(CF 3) 3) 4 -, N(SO 2 CF 3) 2 - N(SO 2 C 4 F 9)2 - and B(C 6 F 5) 4 -; and wherein the unsaturated ketone or unsaturated aldehyde has the formula or wherein Q stands for H or CH 3 and m and p stand independently from each other for a value of 0 to 3 with the proviso that the sum of m and p is 0 to 3, and where a wavy line represents a carbon-carbon bond which is linked to the adjacent carbon-carbon double bond so as to have said carbon-carbon double bond either in the Z or in the E-configuration and where the substructures in formula and represented by s1 and s2 can be in any sequence; and wherein the double bond having dotted lines ( ------) in formula and represent either a single carbon-carbon bond or a double carbon-carbon bond; and wherein ✧ represents a stereogenic centre. P-Q-N stands for a chelating organic ligand comprising a stereogenic centre or has planar or axial chirality and has a nitrogen and phosphorous atom as binding site to the iridium centre of the complex; Y 1, Y 2, Y 3 and Y 4 independently from each other are hydrogen atoms, C 1-12 -alkyl, C 5-10 -cycloalkyl, or aromatic group; or at least two of them form together at least a two-valent bridged group of at least 2 carbon atoms; and Y ⊖ is an anion, particularly selected from the group consisting of halide, PF 6 -, SbF 6 -, tetra(3,5-bis(trifluoromethyl)phenyl)borate (BAr F -), BF 4 -, perfluorinated sulfonates, preferably F 3 C-SO 3 - or F 9 C 4 -SO 3 -; ClO 4 -, Al(OC 6 F 5) 4 -, Al(OC(CF 3) 3) 4 -, N(SO 2 CF 3) 2 - N(SO 2 C 4 F 9)2 - and B(C 6 F 5) 4 -; and wherein the unsaturated ketone or unsaturated aldehyde has the formula or wherein Q stands for H or CH 3 and m and p stand independently from each other for a value of 0 to 3 with the proviso that the sum of m and p is 0 to 3, and where a wavy line represents a carbon-carbon bond which is linked to the adjacent carbon-carbon double bond so as to have said carbon-carbon double bond either in the Z or in the E-configuration and where the substructures in formula and represented by s1 and s2 can be in any sequence; and wherein the double bond having dotted lines ( ------) in formula and represent either a single carbon-carbon bond or a double carbon-carbon bond; and wherein ✧ represents a stereogenic centre. wherein Q stands for H or CH 3 and m and p stand independently from each other for a value of 0 to 3 with the proviso that the sum of m and p is 0 to 3, and where a wavy line represents a carbon-carbon bond which is linked to the adjacent carbon-carbon double bond so as to have said carbon-carbon double bond either in the Z or in the E-configuration and where the substructures in formula and represented by s1 and s2 can be in any sequence; and wherein the double bond having dotted lines ( ------) in formula and represent either a single carbon-carbon bond or a double carbon-carbon bond; and wherein ✧ represents a stereogenic centre.