Charge transport in a Nafion(R) membrane incorporating zinc(II) phthalocyanine (ZnPc) was studied using spectrocyclic voltammetry (SCV) and potential-step chronocoulospectrometry (PSCCS) techniques. The visible absorption spectra of the membrane depended on the ZnPc concentration in the membrane, showing the formation of the ZnPc dimer. The equilibrium constant between the monomer and dimer of ZnPc in the membrane was calculated as 75 M-1. Tt was found that the charge transport occurs by two processes; the first process was considered to be the charge injection from the electrode to the ZnPc present in close proximity to the electrode, and the second one, bulk charge transport in the membrane. The apparent rate constant for the presumed charge injection was estimated as 1.6 x 10(-2) s(-1). The bulk charge transport in the membrane was analyzed as a combination of a physical displacement of ZnPc and charge hopping between them considering the equilibrium between the monomer and dimer of ZnPc. This analysis shows that the charge transport takes place by physical displacement of the ZnPc monomer and not by charge hopping, and that the contribution of the dimer to the charge transport is negligible. The first order rate constant (k(p)) of the physical displacement of the ZnPc monomer was estimated as 3.3 x 10(-3) s(-1). The saturated fraction of the oxidized ZnPc in the membrane decreased with the ZnPc concentration in the membrane because of the bulk charge transfer decreased by the formation of the ZnPc dimer.