The electrochemical properties of polyaniline (PANI) films, grown using multicycling methods, but using two different upper limits, have been examined in detail at three different substrates [Au, Pr, and glassy carbon (GC)]. Overall, type I films are only weakly dependent on the substrate employed. Even so, impedance measurements have shown that type I PANT films (grown by cycling between 0 and ca. 1 V in 0.1 M aniline + 1 M H2SO4), formed on Pt and Au, exhibit the most rapid growth rate, while the highest film pseudocapacitance per unit charge is seen for Pt substrates. Type I PANT has a porosity of 45-50% when formed on Pt and Au, but the porosity is much higher ten. 77%) on GC, inversely correlated with film growth rate. The substrate has a more pronounced effect on the electrochemical properties of type II PANI films (grown by cycling between 0 and 1.7 V in 0.02 M aniline + 1 M H2SO4 solution). This is because type I films are Formed at potentials at which PANT is conducting, while type II are formed primarily when PANI is insulating. Therefore, type I film growth occurs predominantly at the conducting PANI/solution interface, while growth of type II films occurs primarily at the underlying metal/solution interface, causing the substrate properties to become more significant. The growth rate of type II PANI is most rapid on GC, due to the absence of a barrier oxide film, vs, on Pt and Au.