PURPOSE: To obtain the subject compound in a high yield and at a low cost by reacting previously produced glycolonitrile with an ammonium source supplied in a specified molar ratio at such a rate as to keep the pH of the reaction system within a specified range.

CONSTITUTION: In the batch production of iminodiacetonitrile, glycolonitrile (IDAN) is reacted with ammonia and/or an ammonium salt that is not harmful for IDAN formation at 40-150°C, more preferably at 60-110°C by supplying the ammonium source at such a rate as to maintain the molar ratio of glycolonitrile to the ammonium fraction at (1.5-2.5):1 and the pH at 5-7, more preferably at 5.3-6.3. In the case of continuous production, the starting compound is used stoichiometrically at 90-180°C, more preferably at 145-175°C without is controlling pH.