We present the first open-circuit-potential (OCP) study of the chemical polymerization of aniline in the presence of various aromatic additives and demonstrate the feasibility of monitoring the polymerization rate by the OCP technique. With (NH4)2S2O8 as oxidant, there are three stages in the OCP-reaction time plots. The time (t1 + t2) needed for completion of the first two stages is inversely related to the rate of polymerization. The presence of p-aminodiphenylamine, N,N’-diphenylhydrazine, benzidine and p-phenylenediamine reduces the t1 + t2 value and therefore increases the rate of polymerization. In contrast, the presence of p-hydroquinone increases the t1 + t2 value and thus reduces the polymerization rate. These preliminary results are consistent with the kinetics and mechanism of the electrochemical polymerization of aniline.