Benzylaminelglyoxal 1.1:1 mole ratio, strong acid catalysts, esp. perchloric acid, 0.2 mol per mol benzylamine, pH of the glyoxal soln. kept at similar to 5, water added In 10% to the reaction medium, dropwise addition of glyoxal for 3-5 hours at -10 degrees C and later a reaction temp. kept at 35-40 degrees C ensured the title compd. to be prepared In 24 hours In 70% yield. The longer the reaction time, the higher the yield. The steepest rise occurred In the first 24 hours of the reaction.