A process for the production of fatty ketones by pyrolysis of fatty acid magnesium salts wherein fatty acids corresponding to formula (I):R.sup.1 COOH (I)in which R.sup.1 CO is an aliphatic acyl radical containing 12 to 22 carbon atoms and 0, 1, 2 or 3 double bonds, are heated to temperatures of 320.degree. to 360.degree. C. in the presence of magnesium oxide and the fatty ketones formed are distilled off from the reaction mixture under reduced pressure.