Polyaniline (PANT) nanotubes with an outer diameter of 165-240 nm and an inner diameter of 10-70 nm were prepared by a self-assembly process in the presence of six different carboxylic acids-propionic acid (PA), lactic acid (LA), succinic acid (SA), malic acid (MA), tartaric acid (TA), and citric acid (CA)-as the dopants. These nanotubes aggregated to form nanotube dendrites when the carboxylic acids contain an OH group. Moreover, the number of OH and COOH groups of the carboxylic acids affected the size, aggregated dendrite morphology, and thermal and electrical properties of the nanotubes. It was proposed that the micelle formed by the carboxylic acids acts as a template in the formation of the nanotubes, while the hydrogen bonds between the polymer chain of PANI and the OH group of the carboxylic acids supply a driving force to form the aggregated nanotube dendrites.