This study aims at comparing the hydrogen transport in polycrystals and in equivalent homogeneous material, with 3D FE simulations accounting for stress-assisted diffusion and trapping due to plastic strain, in order to examine the hydrogen concentration fields consistency in multi-scale simulations. The effective diffusion features are compared for various sizes of iron polycrystals. For trapping free diffusion, it is shown that hydrogen concentration fields are consistent between scales. When trapping is accounted for, effective diffusion in polycrystals and in homogeneous materials are different, underlying the importance of the trap density function formulation at different scales. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.