Large-area fibrous network of polyaniline is obtained on the surface of diatomite by in situ polymerization of aniline without stirring. And it is characterized via Fourier-transform infrared spectroscopy, Raman spectroscopy, thermal analysis technology, four-probe technique and cyclic voltammetry, as well as specific surface, total pore volume, average pore size and pore size distribution. This composite contains 85% polyaniline, which conductivity is 5.08 S cm(-1) at 25 degrees C. It is more significant that its film electrode not only possesses good redox reversibility in the aqueous media ranging from pH 1.0 to 7.0, but also shows good electrochemical cycling stability in the aqueous media of pH 4.0. It will be a promising material for several applications due to increasing the operating pH window in the aqueous media and good conductivity. (C) 2009 Elsevier B. V. All rights reserved.