A reaction has been discovered by which ketone cyanohydrins CHR·CR'(OH)·CN may be converted into substituted acrylic amides, CHR: CR'·CO·NH2. The reaction proceeds under the influence of concentrated sulphuric acid via the addition compound of this with the cyanohydrin, CH3R·CR'(SO4H) ·CO·NH2. The addition compound splits out sulphuric acid again on heating, yielding the acrylamide. The formation of acrylamides does not occur with aldehyde cyanohydrins. Some suggestions are made to explain the formation of acrylamides from ketone cyanohydrin—sulphuric acid addition compounds.