The following substances have been studied for their chemical activity as expressed by the velocity of replace­ment of the chlorine atom in them (1) Monochlormalondiphenylamide (2) Monochlormalondi-p-tolylamide. (3) Monochlormalondi-o-tolylamide. (4) Nionochlormalondi-1:3:4-xylylamide. The results indicate that the following factors influence the velocity of replacement of the chlorine atom by hydrogen : (i) The positions of the radicals like the methyl groups in the nuclear rings attached to the carbonyl groups, (ii) The molecular weights of the residues carried by the carbonyl groups, (iii) The nature of the nuclei attached to the carbonyl groups between which the carbon atom carrying the chlorine atom is situated.