The influence of the polymerization time and rate as well as the solution's ionic strength on the morphology, conductivity, and molecular structure of the polypyrrole (PPy) microtubule [synthesized by the template-free method in the presence of beta -naphthalene sulfonic acid (beta -NSA) as the dopant] were investigated. It was found that the formation of the PPy-NSA microtubule was a slow and self-assembled growth process, Moreover, the beta -NSA dopant played a "templatelike" role in the formation of tubular PPy-NSA, which might be relative to its surfactant characters. This assumption was further confirmed by the phenomenon that the morphology of PPy-NSA could be modified by increasing the ionic strength by adding inorganic salt. (C) 2001 John Wiley & Sons, Inc.