Polypyrrole/zeolite composites were synthesized by electrochemical polymerization of pyrrole monomer at ambient temperature (22 ± 1 °C) in aqueous suspension of pure microporous zeolite particles. Electrodeposition was performed by using the method of constant potential. The proton form of Beta zeolites with SiO/AlO ratios of 25 and 300 and Y zeolites with SiO/AlO ratios of 12 and 80 was used in this work. The chemical compositions and the acidic properties of the zeolites were studied by inductively coupled plasma optical emission spectrometer and potentiometric acid-base titration. Polypyrrole/zeolite composite films deposited on platinum and indium tin oxide glass electrodes were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy with attenuated total reflectance, X-ray diffraction, and transmission electron micrographs, and their electrochemical behavior was studied by cyclic voltammetry. These measurements showed that polymerization of pyrrole took place on the outer surfaces of the host zeolite crystals. The oxidized cationic polypyrrole was charge-balanced by the anionic groups present in the zeolite framework. Content of the anionic groups in the zeolites was found to be important for the electrochemical behavior of the polypyrrole/zeolite composites. © 2014 Springer-Verlag Berlin Heidelberg.