An original 3D stochastic geometrical model has been developed to simulate the microstructural evolution of porous solid-oxide cell electrodes made of yttria-stabilized zirconia and nickel. The microstructural change induced by Ni agglomeration has been more specifically simulated. The model is based on random sets and algorithms for solving the linear assignment problem related to the time evolution of one component in the microstructure. The possibility to generate realistic 3D microstructures with the model has been verified by comparing the geometrical characteristics of synthetic microstructures with those extracted from real electrode reconstructions. The ability of the Stochastic Time Evolution Microstructure (STEM) model to generate microstructures with evolving characteristics has been then illustrated and compared to real data obtained on aged electrodes. The error on most of the geometrical characteristics are in general lower than 10%, except in some particular cases, such as the microstructure factor. All the results have then been discussed and suggestions have been proposed for improving the model.