A highly conducting polyaniline, doped with a Lewis acid, boron trifluoride, has been synthesized. Doping involves a transfer of the lone pair of electrons from the imine nitrogen of the polyaniline to the B center, leading to a change in the hybridization at the B site from sp(2) to sp(3). Various spectroscopic techniques, in conjunction with ab initio calculations for geometry optimizations, are used to characterize the sample. These techniques all confirm the ability of this electron-deficient molecule to dope polyaniline very effectively, yielding a remarkably high conductivity over a wide temperature range.