An approximate model is developed to describe the voltammetric response for anodic O-transfer reactions at Bi(V)-doped PbO2-film electrodes (Bi-PbO2). Because the Bi(V) sites were found earlier to function for preadsorption of reactant in the anodic O-transfer reactions of cysteine, the model developed here includes reactant adsorption at Bi(V) sites in the Bi-PbO2 surface. The validity of the model is demonstrated on the basis of the voltammetric response obtained for DMSO in 1.0 M HClO4. Good agreement is obtained between predicted and observed values of half-wave potential (E-1/2) as a function of the relative density of Bi(V) sites (rho = Gamma(Bi(V))/Gamma(Pb(IV))) in Bi-PbO2 film electrodes configured as rotated disks. For low site densities (0.11 less than or equal to rho less than or equal to 0.4), E-1/2 is a linear function of ln(rho/(1 + rho)(2)); however, for high site densities (0.4 less than or equal to rho less than or equal to 0.84), E-1/2 is a linear function of ln(1/(1 + rho)). Agreement is also demonstrated for E-1/2 as a function of variations in the rotational velocity of these electrodes. The agreement of the proposed model with experimental data is concluded to be evidence for the importance of reactant adsorption in anodic O-transfer reactions at Bi(V) sites in these Bi-PbO2 electrodes.