A process for reductive amination of aliphatic cyanoaldehydes to aliphatic diamines comprising (1) providing a mixture of 1,3-cyanocyclohexane carboxaldehyde and/or 1,4-cyanocyclohexane carboxaldehyde; (2) contacting said mixture with a metal carbonate based solid bed or a weak base anion exchange resin bed at a temperature from 15 to 40 ° C. for a period of at least 1 minute; (3) thereby treating said mixture, wherein said treated mixture has a pH in the range of 6 to 9; (4) feeding said treated mixture, hydrogen, and ammonia into a continuous reductive amination reactor system; (6) contacting said treated mixture, hydrogen, and ammonia with each other in the presence of one or more heterogeneous metal based catalyst systems at a temperature from 80 ° C. to 160 ° C. and a pressure from 700 to 3500 psig; (7) thereby producing one or more cycloaliphatic diamines is provided.