Based on the analysis of the authors’ own experimental data on the chemical oxidative polymerization of aniline (ANI), as well as on the results of other authors on the electrochemical oxidation of ANI and the electrochemical response of the polyaniline (PANI) film obtained, the conclusion has been drawn that the polymerization of ANI can be considered both as a cationic polymerization and as a normal redox process. Summarizing, the conditions of initiation, propagation and termination of the chains can be expressed by the value of the electrochemical potential (EP) of the system. When the EP is kept at a value higher than c. 0.55V, the polymerization can be regarded as a living cationic polymerization. In this case, PANI with an oxidation state (OS) higher than emeraldine is obtained. Thermodynamically reversible termination takes place when the EP of the system drops to a value less than c. 0.5V. In this case, the oxidative polymerization of ANI can be regarded as a quasi-living cationic polymerization, and PANI of emeraldine OS is obtained.