Without using any adjustable parameter, the temperature and pressure dependences of oxygen self-diffusion coefficients in Mg2SiO4 polymorphs (forsterite, wadsleyite and ringwoodite) and MgSiO3 perovskite have been successfully reproduced from the cB Omega model that interconnects point defect parameters with bulk properties under the corresponding P-T conditions of the lower mantle. In addition, an alternative method is proposed to calculate the pre-exponential factor of oxygen diffusion coefficients from the measurements of the electrical conductivity through the Nernst-Einstein equation, which is based on an observed compensation law between activation energies and pre-exponential factors for the electrical conductivity of forsterite and MgSiO3 perovskite. In most cases, our results show the cB Omega model does better than the latter approach, and the self-diffusion coefficients values derived from the cB Omega model agree fairly well with the experimental ones if the relevant uncertainties are considered. Furthermore, the cB Omega model is also found to give a correct estimation of the activation enthalpy and volume for MgSiO3 perovskite. However, the calculated activation enthalpies and activation volumes of O diffusion in Mg2SiO4 polymorphs are shown to differ substantially between our empirical estimates and the theoretical calculations. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.