Polyaniline him has been grown onto a platinum electrode by electrochemical polymerization from an anilinium tetrafluoroborate + acetonitrile solution. The anilinium tetrafluoroborate salt was characterized by H-1 NMR and IR spectroscopies. The electropolymerization procedure does not require the use of a supporting electrolyte thus facilitating the optimization of the process. The electropolymerization efficiency of polyaniline from the aforementioned solution is low as is indicated by the low doping level evaluated from the cyclic voltammetry data and the charge consumed during polymer growth.