Abstract: Copolymerization of acrylamide and sodium acrylate initiated by K₂S₂O₈-NH₂CONH₂ was studied. The molecular weight and composition of copolymers can be effectively con-trolled by addition of various amounts of chain-transfer agent and by changing the pH and temperature of reaction system up to 98-100% conversion. Water-soluble copolymers with intrinsic viscosity of 2-28dl/g and sodium acrylate content of 0-100 mol.% were obtained.The copolymers were found to be in agreement with that of second order Markov process by ¹³C-NMR determination.