Mercaptoacetonitrile synthesis

The process of forming mercaptoacetonitrile which comprises reacting in mass a substantially stoichiometric amount of chloroacetonitrile with a 10 to 50 weight % aqueous solution of sodium hydrosulfide at a temperature in the range -25.degree. C. to -10.degree. C. in an inert atmosphere at a pressure ranging from substantially atmospheric up to about 30 mm Hg above atmospheric and maintaining the reaction mixture at a temperature below 5.degree. C. after the exotherm peak.