The understanding of oxygen self-diffusion over a range of temperatures is important in UO2 and ThO2 particularly for nuclear fuel applications. A way to realize this is by the cB Omega model in which the defect Gibbs energy is proportional to the isothermal bulk modulus (B) and the mean volume per atom (Omega). In the present study elastic and expansivity data is used in the framework of the cB Omega model to derive the oxygen self-diffusion coefficient in UO2 and ThO2 in the temperature range of 2000 K to 3000 K. The derived results are in excellent agreement with the most recent experimental and theoretical data. (C) 2015 Elsevier B.V. All rights reserved.