A Kinetic Monte Carlo (KMC) model is presented which simulates the open-circuit voltage and electrical double layer of a doped electrolyte. The computational grid approximates the defect spacing in an electrolyte, so the length scale is atomistic. Numerical results for steady state, open-circuit voltage match analytical predictions over a wide range of oxygen pressure differentials. A general analytical solution is then presented for the distribution of ions in a doped electrolyte subjected to an external voltage. Using available data for Yttria-Stabilized Zirconia (YSZ), it is found that the KMC simulator computes ion concentration profiles and electrical double layers in close agreement with the predictions of the analytical model. A localized or differential updating scheme is used for the electric field that significantly reduces the computation time. (c) 2005 Published by Elsevier B.V.