Electrically detected magnetic resonance ͑EDMR͒ and electron paramagnetic resonance ͑EPR͒ were used to investigate emeraldine base polyaniline films. The magnetic susceptibility presented a Curie ͑localized spins͒-Pauli ͑delocalized spins͒ transition at 240 K, when we also observed a transition in the dependence of the g factor with temperature ͑T͒. Peak-to-peak linewidth decreases with increasing temperature, reflecting that motional narrowing limits the hyperfine and dipolar broadening in this polymer. EDMR spectra could only be observed above 250 K in accordance to EPR results. Surface and bulk transport could be separated and their analysis reflected the effect of magnetic interaction with oxygen.