Aluminium surfaces were microstructured in 0.1 M HNO3 by potentiodynamic anodic activation to potentials generating pitting. This surface was then used as an electrode to prepare polyaniline powder. The number of pits is responsible for the amount of powder produced. Emeraldine salt powder was successfully prepared from 0.4 M aniline in 0.5 M H2SO4 solution. Other acid solutions for deposition are not convenient because powders are electrochemically inactive (e.g., in 1 M HNO3) or the electrode is covered by a film (e. g., in 0.5 M H2C2O4).