Porous polyaniline (PANI) films with high conductivity at room temperature have been prepared by a new method called 'doping-dedoping-redoping'. The room-temperature conductivity of the resulting PANI films doped with HCl, HClO 4 , H 2 SO 4 , H 3 PO 4 and p-toluene sulfonic acid (p-TSA), can reach 200-300 S cm - 1 , which is comparable with the results of PANI films doped with camphor sulfonic acid (CSA) in m-cresol. It has been demonstrated that the resulting PANI chains still keep the expanded conformation like PANI-CSA in m-cresol, which may be why high room-tenmperature conductivity can be obtained by this new method. Moreover, the electrical and mechanical properties of the resulting PANI films have been measured as a function of the protonation state, temperature and dopants.