Exploitation of the redox properties of polyaniline has made possible the formation of a meltable crystalline phase in the leucoemeraldine base form of the polymer. Both fibres and films exhibiting the melting transition were prepared from leucoemeraldine base/N,N＇-dimethyl propylene urea solutions. This melting behaviour is confirmed by a battery of experimental methods : thermogravimetric analysis, differential scanning calorimetry, optical microscopy, dynamic mechanical analysis and x-ray diffraction. This melting transition raises the possibility of future melt processing of polyaniline.