An interrelationship between the mechanism of aniline polymerization and the direction of redox processes with participation of polyaniline chains on the one hand, and the pi-electron energy of oligoanilines with various numbers of units, degrees of oxidation and protonation on the other hand, has been found for the first time. Calculations performed using the Hueckel method revealed that the difference in the pi-electron energy of the oxidized and reduced forms of the chain correlated very well with the experimentally determined electrochemical potential for the respective redox transition. It is suggested that the Hueckel method can be used for investigation of the electrochemical activity of conjugated polymers obtained by oxidative polymerization, as well as for studying the mechanism of the latter.