Electrocatalytic effects on electropolymerization of aniline were investigated. It was determined that surface catalysis by beta-PbO2 causes formation of higher amounts of polyaniline than catalysis by alpha-PbO2 and Pb2+ ions. beta-PbO2 surfaces decreased the upper potential limit of aniline electropolymerization about 400 mV. The catalytic effect of PbO2 is highly dependent upon the crystal structure of PbO2. Dry conductivity values of polyaniline samples obtained under different conditions were also compared.