Charge transport in a Nafio((R)) membrane with dispersed cis-[Ru(bPY)(2)(H2O)(2)](2+) or [Ru(terpy)(2)](2+) was investigated using potential-step chronoamperospectrometry. The apparent diffusion coefficient of charge (D-app) for cis-[Ru(bpy)(2)(H2O)(2)](2+) increased linearly with increasing temperature in low temperature regions, reaching a plateau at higher temperature suggesting the existence of different mechanisms in the low and high temperature regions. The diffusion coefficient for cis-[Ru(bPY)(2)(H2O)(2)](2+) increased with an increase in concentration at 298 K, while it decreased slightly at 278 K, which was attributed to the suppression of self-exchange of electrons between molecules at 278 K. A percolation threshold was observed at 0.3 M in the concentration dependence of the diffusion coefficient for [Ru(terpy)(2)](2+) at 298 K. The charge hopping distance for [Ru(terpy)(2)](2+) was estimated as 0.9 nm based on the percolation theory. The self-exchange rate constants of electrons at 298 K were estimated in the order, [Ru(bPY)(3)](2+) approximate to [Ru(terpy)(2)](2+) > cis-[Ru(bpy)(2)(H2O)(2)](2+) suggesting that the self-exchange rate increases with increasing molecular size.