A fast, simple, and environmentally friendly new electrochemical method capable of enhancing the conductivity of a preformed polyaniline film has been found. Utilizing this method of electrochemical forcing pretreatment at a certain effective voltage, a polyaniline solid matrix can be made more conductive. For example, the conductivity of a preformed polyaniline film (as thick as 10 mum) can be easily enhanced by about an order of magnitude within a pretreatment time of only ca. 5 min. The UV-vis-NIR and ESR spectroscopic evidences indicated that the charge carriers in the polyaniline matrix are more delocalized after such electrochemical pretreatments. The results of CV studies indicated that the resultant polyaniline film has higher charge transport efficiency and a greater redox rate. Such phenomenon may be linked with a possible backbone conformational change, as induced by this novel electrochemical pretreatment, within the solid matrix of polyaniline film.