Abstract: The present invention includes a process for the preparation of a lactam by vapor phase reaction of an aliphatic aminonitrile with water in the presence of a solid catalyst, wherein the catalyst is an alumina having a specific surface, measured by the BET method, greater than or equal to 10 m2/g. The alumina catalyst is further characterized by either: (a) a specific surface less than or equal to 280 m2/g, and a volume of pores with a diameter greater than 500 Å which is greater than or equal to 10 ml/100 g; or (b) a specific surface greater than or equal to 50 m2/g and less than or equal to 280 m2/g, and a volume of pores with a diameter greater than 70 Å which is greater than or equal to 30 m2/g.