Abstract Polypyrrole (PPY) composite powders doped with RuCl3·xH2O of variable mass were prepared by a way of in situ chemical polymerization. Their electrochemical properties were investigated with cyclic voltammetry, charge–discharge tests and ac impedance spectroscopy in 1M NaNO3. Morphology and crystalline structure of these Ru-doped PPY powders were examined by transmission electron mi…