The nanothread of polyaniline (PANI) using ammonium persulphate ((NH4)(2)S2O8) as an oxidant was prepared. The solution is composed of 0.4 mol dm(-3) aniline, 1.0 mol dm(-3) hydrochloric acid, and different proportions ethanol. The resulting products were characterized using infrared spectroscopy, UV-vis spectra, transmission electron microscope, thermogravimetric analysis techniques, and Xray diffraction. The experimental results show that the content of ethanol has effects on the morphology of PANI, but the effects on the conductivity are not very obvious. When the volume ratio of ethanol to aniline is 1:2, the more uniform and regular PANI nanothread can be prepared. (c) 2005 Wiley Periodicals, Inc.