By the methods of classical and oscillographic polarography, electrolysis with controlled potential and spectrophotometry, the mechanism of electrochemical generation and the active centers nature of anionic polymerization of methyl methacrylate in dimethylformamide was investigated. It was shown that in dimethylformamide in the presence of tetraalkylammonium cations, methyl methacrylate carbanions exist as solvately divided ion pairs in which the electrostatic interaction is determined by the radius of the cation. It affects the chemical stages rate of the electrochemical generation of carbanions and appears by the anomalous shift of ζ 1/2 of polarographic reduction with the increasing of the cation radius of the supporting electrolyte. The replacement of the lithium cation with tetraalkylammonium changes the interaction type of methyl methacrylate carbanion with the counterion.