Polypyrrole and poly(4-(3-Pyrrolyl)butane-sulfonate) films were electrodeposited potentiostatically or by potential cycling on Pt substrates. The growth behavior for electropolymerization of pyrrole and 4-(3-Pyrrolyl)butane-sulfonate was examined via an Electrochemical Quartz Crystal Microgravimetry (EQCM) in situ. The effects of pyrrole and 4-(3-Pynolyl)butane-suIfonate concentration on the deposition rate (g/s) and the chronoamperometric responses were investigated. Additionally, the surface morphology of conductive polymer films were observed with atomic force microscopy (AFM). The polypyrrole film deposited electrochemically by potential cycling thickens with the forward and reverse scan. However, the poly(4-(3-Pynolyl)butane-sulfonate) film stopped growing during the reverse scan. The deposition rate of poly(4-(3-Pyrrolyl)butane-sulfonate) is linearly dependent on the 4-(3-Pynolyl)butane-suIfonate concentration. However, the deposition rate of polypyrrole depends nonlinearly on the pyrrole concentration.