Abstract: Ethylenediamine tetraacetonitrile is prepared in a two stage process by cyanomethylating an ethylenediamine formaldehyde adduct with hydrocyanic acid at 30.degree. C. or less under basic conditions (pH 8 to 10) to form, in a first discrete stage, ethylenediamine diacetonitrile (EDDiN) which is soluble in the reaction mixture. The solution of EDDiN is then further cyanomethylated under acidic conditions with formaldehyde and hydrocyanic acid in slight excess to form ethylenediamine tetraacetonitrile (EDTN). The precipitated EDTN, with or without isolation, can be hydrolyzed to form ethylenediamine tetraacetic acid in a stock solution for further processing. The process reduces the need for toxic cyanide waste treatment and greatly simplifies the procedures needed to protect the environment.