Microstructure of a cermet Ni–YSZ bi-layer is analysed on the basis of three dimensional reconstructions obtained on both functional layer and cell support. Microstructural parameters of gas, ionic and electronic phases are determined in terms of phase connectivity, mean particles diameter, particles size distribution, specific surface area, tortuosity factor and density of TPBls. Microstructural properties are introduced in an SOEC cathode micro model that takes into account the specific configuration of the Ni–YSZ composite bi-layer. Simulations show that the extent of the electrochemical reaction in the support is very limited. Moreover, it is found that electrode apparent activation energy is a combination of effective ionic conduction and charge transfer in the active functional layer.