Potentiometric and calorimetric measurements on aniline polymerized by persulfate reveal an induction period, which may be decreased or eliminated by the addition of eerie (Ce-IV) ion. The addition of the second oxidizer appears to promote nucleation. The molecular weight and electrical conductivity of the resulting polyaniline were measured. Substantial shortening of the reaction time and improvement of polymer conductivity may be realized with the addition of 0.1-1% Ce-IV co-oxidizer in the standard polymerization technique using persulfate. Ultraviolet/visible spectroscopy of polymer solutions suggests that significant oxidative degradation is responsible for poor conductivity of polymer made using lar amounts of Ce-IV.