The spontaneous polymerization of (meth)acrylamide and its derivatives in concentrated aqueous solutions was studied in the presence of inorganic and organic acids. The regularities of the process were defined depending on the structure of the monomers, concentration of the monomers and acid additives, and the nature of anions and cations in the system. It was demonstrated by the methods of viscosimetry and NMR spectroscopy, that (meth)acrylamides in concentrated aqueous solutions form monomeric associates. The hypothesis was suggested, that the polymerization occurs in monomeric associates and is initiated via electron transition from an anion to a C = C bond. (C) 2004 Elsevier Ltd. All rights reserved.