The potential-step chronoamperospectrometry (PSCAS) measurement was carried out to study the electron transport by methylviologen (MV2+) attached by electrostatic interaction or chemical bonding to a polymer film coated on an ITO electrode. In this system composed of MV2+ and a Nafion(R) film, the electron transport occurred by physical diffusion of the viologen and its apparent first order rate constant was 1.4 X 10(-1)s(-1). In the latter chemically bonded system composed of poly(styrene)-pendant MV2+, the electron transport took place by electron hopping between the pendant viologens, and the electron transfer distance between the adjacent redox centers, calculated based on a random distribution, increased with the sample time of the PSCAS measurement to attain the distance of 0.92 nm.