Addition of triflate salts to the emeraldine base form of polyaniline in the solid state causes a lowering of its work function but not an increase of its conductivity. It is postulated that this effect is due to the formation of localized energy states in the band gap. On the other hand, strong protonic acids such as triflic acid as well as tetrafluoroboric acid lower both the work function and increase the conductivity of PANI-EB according to the known protonic form of the doping mechanism. The difference between these two kinds of doping has been demonstrated by measurement of the work function, conductivity, UV-vis, and IR spectroscopy.