RE 1+x Ba 2-x Fe 3 O 8+δ (RE = Pr, Nd, Sm, …) have been presented recently as potential electrode materials for Solid Oxide Fuel Cells. Depending on the composition, these materials may present a disordered cubic perovskite phase, an ordered quintuple perovskite or a mixing of both. Such an evolution in the structure potentially affects oxygen ion diffusion at the core of the air electrode property. In the present study based on molecular dynamics simulations, we explore the influence of cation order on oxygen diffusion properties. We determine both macroscopic diffusion coefficients and also extract some information about atomic scale mechanisms. Similarly to previous results on double cobaltites, we explore if the disordering of A-site cations favours or not oxygen diffusion in these ferrites. We finally show that the nano-ordering, as observed experimentally, leads to a slight improvement of the oxygen ions diffusion process compared to the fully ordered structure, having its oxygen diffusion coefficient much smaller than the one of the disordered structure.