The influence of nonuniform current and potential distributions associated with a disk electrode geometry on the impedance response was explored by numerical simulation for faradaic reactions coupled by an adsorbed intermediate. Consistent with the literature, the associated frequency or time-constant dispersion influenced the impedance response at frequencies above a characteristic value due to the frequency dependence of the radial distribution of the interfacial potential. The time-constant dispersion was also found to influence the impedance response at low frequencies due to the potential dependence of the fractional surface coverage of the adsorbed intermediate. The geometry effects were reflected in values for the local ohmic impedance, which had complex behavior at both high and low frequencies. The dispersion of time constant was described in terms of a local constant-phase element (CPE) that represented the impedance response at low frequencies as well as at high frequencies. A graphical method is described for finding values for the CPE exponent.