Process for deoxygenation of carboxamides and carboxylic esters by cathodic reduction of a solution of the carboxamide or the carboxylic ester, characterized in that the solution comprises a salt as additive which is selected from among quaternary ammonium salts and the cation of the salt has the formula I where k is an integer in a range from 1 to 99 and is in particular 1 or 2, A is nitrogen Z is an alkylene group having 2 to 12 carbon atoms, wherein optionally 1, 2 or 3 CH 2 groups, which are separated from the nitrogen atoms A and from each other by at least 2 carbon atoms, may be replaced by oxygen atoms, R 1, R 2, R 3 and R 4 are each independently C 1 -C 10 -alkyl, which in each case is unsubstituted or may be substituted with 1 or 2 substituents selected from hydroxyl, alkoxy and poly(oxyethylene), or R 1 and R 2, together with the nitrogen atom to which they are bonded, may also be a 5- to 8-membered heterocycle which comprises 1 nitrogen atom in the ring and is unsubstituted or may be substituted with 1 to 4 substituents selected from hydroxyl, C 1 -C 4 -alkoxy and C 1 -C 4 -alkyl, R 5 and R 6 are each independently C 1 -C 10 -alkyl, which in each case is unsubstituted or may be substituted with 1 or 2 substituents selected from hydroxyl, alkoxy and poly(oxyethylene), and a carboxamide or a carboxylic ester of the formula II is used, where Y is a chemical bond or an alkylene group having 1 to 6 carbon atoms, X is oxygen or N-R 9, R 7 is selected from C 1 -C 10 -alkyl, C 2 -C 10 -alkenyl, C 1 -C 10 -alkoxy, C 1 -C 10 -haloalkyl, C 1 -C 10 -haloalkoxy, C 3 -C 10 -cycloalkyl, aryl and hetaryl, wherein the ring in the latter three groups mentioned is unsubstituted or may be substituted with up to 6 substituents selected from halogen, hydroxyl, C 1 -C 4 -alkyl and C 1 -C 4 -alkoxy, and R 8 is selected from hydrogen, C 1 -C 10 -alkyl, which is unsubstituted or has 1 or 2 substituents selected from hydroxyl, C 1 -C 4 -alkoxy and aryl, C 2 -C 10 -alkenyl, C 1 -C 10 -haloalkyl, C 1 -C 10 -haloalkoxy, C 3 -C 10 -cycloalkyl, aryl and hetaryl, wherein the ring in the latter three groups mentioned is unsubstituted or may be substituted with up to 6 substituents selected from halogen, hydroxyl, C 1 -C 4 -alkyl and C 1 -C 4 -alkoxy, where R 8 is different from hydrogen if X is 0, R 7 and R 8 may together be C 3 -C 20 -alkylene or C 3 -C 20 -alkenylene, which is unsubstituted or is substituted with up to 6 substituents selected from hydroxyl, C 1 -C 4 -alkyl and C 1 -C 4 -alkoxy, wherein 2 substituents bonded to adjacent carbon atoms, together with the carbon atoms to which they are attached, may also form a 5- to 7-membered carbocycle; and R 9 is hydrogen or C 1 -C 10 -alkyl, which is unsubstituted or has 1 or 2 substituents selected from hydroxyl, C 1 -C 4 -alkoxy and aryl. k is an integer in a range from 1 to 99 and is in particular 1 or 2, A is nitrogen Z is an alkylene group having 2 to 12 carbon atoms, wherein optionally 1, 2 or 3 CH 2 groups, which are separated from the nitrogen atoms A and from each other by at least 2 carbon atoms, may be replaced by oxygen atoms, R 1, R 2, R 3 and R 4 are each independently C 1 -C 10 -alkyl, which in each case is unsubstituted or may be substituted with 1 or 2 substituents selected from hydroxyl, alkoxy and poly(oxyethylene), or R 1 and R 2, together with the nitrogen atom to which they are bonded, may also be a 5- to 8-membered heterocycle which comprises 1 nitrogen atom in the ring and is unsubstituted or may be substituted with 1 to 4 substituents selected from hydroxyl, C 1 -C 4 -alkoxy and C 1 -C 4 -alkyl, R 5 and R 6 are each independently C 1 -C 10 -alkyl, which in each case is unsubstituted or may be substituted with 1 or 2 substituents selected from hydroxyl, alkoxy and poly(oxyethylene), and Y is a chemical bond or an alkylene group having 1 to 6 carbon atoms, X is oxygen or N-R 9, R 7 is selected from C 1 -C 10 -alkyl, C 2 -C 10 -alkenyl, C 1 -C 10 -alkoxy, C 1 -C 10 -haloalkyl, C 1 -C 10 -haloalkoxy, C 3 -C 10 -cycloalkyl, aryl and hetaryl, wherein the ring in the latter three groups mentioned is unsubstituted or may be substituted with up to 6 substituents selected from halogen, hydroxyl, C 1 -C 4 -alkyl and C 1 -C 4 -alkoxy, and R 8 is selected from hydrogen, C 1 -C 10 -alkyl, which is unsubstituted or has 1 or 2 substituents selected from hydroxyl, C 1 -C 4 -alkoxy and aryl, C 2 -C 10 -alkenyl, C 1 -C 10 -haloalkyl, C 1 -C 10 -haloalkoxy, C 3 -C 10 -cycloalkyl, aryl and hetaryl, wherein the ring in the latter three groups mentioned is unsubstituted or may be substituted with up to 6 substituents selected from halogen, hydroxyl, C 1 -C 4 -alkyl and C 1 -C 4 -alkoxy, where R 8 is different from hydrogen if X is 0, R 7 and R 8 may together be C 3 -C 20 -alkylene or C 3 -C 20 -alkenylene, which is unsubstituted or is substituted with up to 6 substituents selected from hydroxyl, C 1 -C 4 -alkyl and C 1 -C 4 -alkoxy, wherein 2 substituents bonded to adjacent carbon atoms, together with the carbon atoms to which they are attached, may also form a 5- to 7-membered carbocycle; and R 9 is hydrogen or C 1 -C 10 -alkyl, which is unsubstituted or has 1 or 2 substituents selected from hydroxyl, C 1 -C 4 -alkoxy and aryl.