An orchid-like polyaniline (PANI) structures was synthesized by initialing the polymerization at 80 degrees C and growing at 25 degrees C using ethanol and water as co-solvent in the presence of toluene-p-sulfonic acid (p-TSA) as the dopant. The "flowers" are consisted of 8-14 pieces of "petals" with 5-8 mu m in length. By adjusting the molar ratio of p-TSA/aniline, the cooling rate and the component of the solvent, flake-like and peony-like morphology can also be obtained. The formation mechanism of the orchid-like structure is proposed. (C) 2011 Elsevier Inc. All rights reserved.