Recent theory has shown that, in transient electrochemical oxidation or reduction of a redox polymer film, electroneutrality coupling between concurrently transported electrons and counterions in the polymer film can enhance the rate of electron-hopping transport as expressed by the apparent electron diffusion coefficient D-e,D-app. We have investigated this problem in the redox polymers poly [Os(2,2’-bipyridine)(2)(N-(4-pyridyl)cinnamamide)(2)](2+) (poly-I), poly[Os(2,2’-bipyridine)(2)(4-vinylpyridine)(2)](2+)(poly-II), and poly[Os(4-vinyl-4’-methyl-2,2’-bipyridine)3](2+)(poly-III) by measuring and comparing the diffusion coefficients (D-cl) of Cl- counterions in the cationic polymer Alms to the transient chronoamperometric (D-e,D-app) and steady-state (D-e) electron diffusion coefficients. At room temperature, the ratio sigma=D-ion/D-e is 1.25, 0.16, and 0.076 for the three redox polymers, respectively. According to the electroneutrality coupling theory, the coupling effect is insignificant in poly-I films at room temperature, with and without dilution of the Os centers by copolymerized Ru complexes, but at lowered temperature, assuming sigma-->0, coupling in poly-I has a substantial effect. Electroneutrality coupling in poly-III films enhances the room temperature chronoamperometric D-e,D-app over the ("true") steady-state’D-e value by ca.2-fold. The lack of agreement between experiment and bimolecular electron self-exchange for microscopic (bounded) diffusion of Os sites, as reflected in an Os site concentration-dependent activation barrier for D-e,D-app.