Polyaniline modified electrodes were prepared following a two step procedure : (i) electrodeposition of manganese dioxide from an alkaline permanganate solution, and (ii) chemical polymerization of aniline on the electrode surface by a manganese dioxide layer. Electrochemical behaviour of the obtained polyaniline films was studied, and a large amount of an alternative polymer was found to be formed. The amount of alternative polymer increases with an increase of a temperature used in manganese dioxide deposition step.