The temperature dependence of the magnetic susceptibility of polyaniline at significant different doping levels has been investigated. The samples cover the conducting as well as the insulating region. The conductivity varies from 10(-4) to 5 S cm(-1). A temperature independent behaviour of the spin susceptibility is found in all cases. While the interpretation of the temperature dependence was formerly done by assuming metallic properties (Pauli paramagnetism) we give an alternative explanation of the results here based on the temperature dependence of a chemical equilibrium. (C) 2004 Elsevier B.V. All rights reserved.