This paper presents a novel methodology to calculate cation diffusion coefficients and activation energies in cubic Y(2)O(3)-ZrO(2) by Molecular Dynamics. The calculation is based upon modulating the interaction potential to promote cation mobility within the lattice. The technique was calibrated by measuring static properties and oxygen self-diffusion characteristics, and then applied to cation diffusion. The respective activation energies and diffusion coefficients agree well with experimental findings. Preliminary results about grain boundary cation diffusion are presented for the first time as a proof of the potentiality of the procedure. (C) 2011 Elsevier B.V. All rights reserved.