When studying polymerization in the presence of bis-triphenylmethyl barium (TPM-Ba) in THF the effect of the type of alkyl group combined with the initiator on elementary stages of chain extension was established for the first time for processes of anionic polymerization initiated by non-transition metal compounds. It was shown that the compositions of initial copolymers formed by the action of TPM-Ba are similar to those of the initial monomer mixture, whereas copolymers obtained by the action of other organic barium initiators under similar conditions have a much higher styrene content. A study of results and information concerning kinetics of separate polymerization indicate that the presence of a triphenyl methyl group in the composition of the active centre markedly reduces the rate of elementary processes taking place with monomeric styrene.