The study of electron relaxation and dynamics of polaron charge carriers in undoped and H₂SO₄-doped polyaniline (PANI) by means 3-cm (9.7 GHz) and 2-mm (140 GHz) EPR spectroscopy, ac SQUID and dc conductometry is reported. The existence in PANI of polarons with different relaxation and mobility is shown. Spin-lattice and spin-spin relaxation times as well as the intrachain diffusion and interchain hopping rates of these centres were determined separately at 90 – 330 K by steady-state saturation method at 2-mm waveband EPR. At the polymer doping an effective spin relaxation decreases due to formation of the metal-like domains of well coupled chains with 3D delocalized charge carriers. The mechanism of spin and charge transfer in PANI with different doping levels is analyzed. The macro- and microconductivity of the medium doped PANI is determined by 3D inter- and intradomain hopping of charge carriers, respectively. In heavily doped polymer the dominating is 1D interdomain and 3D interchain Mott variable range charge hopping accompanied with a strong interaction of the charge with the lattice phonons. It is shown that bipolaron is a preferred charge carrier in doped PANI samples