A facile and efficient route for the homogeneous and highly stereoselective monohydration of substituted methylenemalononitriles to (E)-2-cyanoacrylamides catalyzed by copper(II) acetate monohydrate in acetic acid containing 2% water is described, and a mechanism is proposed. The protocol has proved to be suitable for the monohydration of dicyanobenzenes and 2-substituted malononitriles.