The formation of polyamines and hcxamethyleneimine is sup- presscd in the presence of NH,. These can form from both nitrile groups by hydrogenation to thc aldimine, reaction of the aldimine with amine to split off NH, and give the azomethinc, followed by hydrogenation to the secondary amine. The secondary amine is also capable of adding to the aldimine inter- mediates. The selectivity to hcxamcthylenediamine is about 90 to 95%.