PURPOSE: To obtain N-vinyl amide having a high conversion rate and high selectivity at a relatively low temp. at which harmful hydrogen cyanide, which is a byproduct, is less formed.

CONSTITUTION: The objective compd. of formula II is obtd. by heating the compd. of formula I (R1 is H, 1 to 6C alkyl, 5 to 9C aryl, substd. aryl; R2 is 1 to 9C alkoxy, carboxy, carboxamide), for example, ethylidene bis(folmaldehyde) at about 210 to 350°C under a pressure of preferably about 3 to 3,000 Torr, more preferably 3 to 1,000 Torr in the presence of a porous catalyst consisting of oxide of Mgs or Ca and/or Sr. This reaction may preferably by effected in the presence of an inert gaseous diluent selected from 20 to 80 mol% Ne, H2 and Ar on the basis of the supply materials. In such a case, the diluent achieves the low partial pressure of the carboxylic acid amide in the reaction width and increases the heat transfer to or from a catalyst bed. thus increasing the average free route of molecules and attaining a higher space/time yield.