The electrochemical formation of polyaniline (PAn) was investigated in selenic acid. The cyclic voltammetry of selenate in the potential window from -0.15 to 0.8 V, indicates that the electropolymerization of aniline is not affected by the oxidizing ability of selenic acid. The growth rate of PAn observed at a potential of 0.8 V in a solution of 0.1 M aniline in 0.2 M H2SeO4 was comparable with that in 0.2 M H2SO4. However, the PAn growth in H2SeO4 during successive potential cycles between -0.15 and 0.8 V was much lower than that in H2SO4. In cyclic voltammograms, the first reduction peak for PAn was enhanced by the presence of selenate ions, possibly due to the deposition of elemental selenium catalyzed by the polymer film. The deposition of metallic selenium on the PAn film greatly inhibited the growth of the polymer during successive potential cycling between -0.15 and 0.8 V.