PURPOSE: To advantageously execute the catalytic hydrogenation of carboxylic acid halides to aldehyde in the presence of an alkylene oxide.

CONSTITUTION: At the time of the catalytic reduction of carboxylic acid halides with hydrogen, it is executed in the presence of an alkylene oxide (butylene oxide, propylene oxide and ethylene are particularly suitable). This method can easily be executed in the presence of an inert organic solvent such as hydrocarbon such as petroleum ether, toluene or the like or halogenated hydrocarbon such as methylene chloride or the like. The method is particularly suitable for the production of acid-unstable or base-unstable aldehydes such as α- aminoaldehyde.