Abstract: Iminodiacetonitrile is prepared by a process comprising: (a) forming an aqueous reaction mixture by admixing water, hexamethylenetetramine, formaldehyde, and HCN; and (b) forming iminodiacetonitrile by passing the aqueous reaction mixture through a continuous reaction zone while maintaining the temperature within the continuous reaction zone at 50.degree.-250.degree. C. The resulting iminodiacetonitrile can be recovered or it can be hydrolyzed to form an alkali metal salt of iminodiacetic acid which can be recovered or converted to iminodiacetic acid which can be recovered.In other embodiments: (a) the hexamethylenetetramine solution and the formaldehyde solution can be combined before being admixed with the HCN; or (b) the formaldehyde solution and the HCN can be admixed with a stabilizing acid to form an acid stabilized aqueous solution of formaldehyde and HCN before being admixed with the hexamethylenetetramine solution in the reaction zone in which iminodiacetonitrile is formed.