The reaction kinetics of the chemical polymerization of aniline in aqueous acid solutions with FeCl3 as the oxidant (initiator) was investigated at 25 oC. The polymerization was performed in a special reactor which enabled the initial concentration of oxidant to be kept constant during the polymerization reaction. The order of the reaction of ANI polymerization with respect to FeCl3 was calculated as n = 0.18. The rate constant k of the polymerization reaction was found to be 9.1x10-5 (mol dm-3)-1,18 s-1. The theoretical yield of the reaction was calculated using the Faraday law and the experimentally determined quantity of electricity exchanged during the polymerization reaction. There was a discrepancy between the experimentally and theoretically determined yield, indicating that the oxidant was being consumed in some side reactions, which is an accordance with the fact that the order of the reaction of ANI polymerization with respect to FeCl3 is a non-integer number.