Radially aligned polyaniline dendrites with nanotube junctions have been synthesized using tartaric acid as the dopant without the aid of any surfactants. These dendritic nanotubes with 80-400 nm in outer diameter, 30-50 nm in wall thickness, and several micrometers in length can self assemble into urchin-like nanostructures. The geometrical shape of the individual branch is a cone. The nanotube junctions may provide potential applications in nanoelectronic devices. Furthermore, the influences of other organic acid, such as citric acid, oxalic acid, and acrylic acid, on the morphologies on polyaniline nanostructures have been investigated. (c) 2005 Elsevier Ltd. All rights reserved.