The hydrolysis of two acetimidate esters (I and II) derived from aniline and α-methylphenethylamine has been studied at 30° in the pH range 0-12. Hydrolysis yields amines and esters in acid solution and amides at alkaline pH, transition between the two sets of products taking place at pH 7.69 and 8.45 for I and II, respectively. At constant pH, bifunctional catalysts (phosphate, bicarbonate, acetic acid) divert the breakdown of tetrahedral intermediates from the formation of amides to the expulsion of amines. The mechanism previously proposed to account for iminolactone hydrolysis seems to hold generally for the hydrolysis of imidates. This mechanism involves the intermediacy of carbinolamine addition compounds whose breakdown is influenced by pH and by general acid-base catalysts. Implications of this work for the mechanism of ester aminolysis are discussed. © 1968, American Chemical Society. All rights reserved.