A spherical copper powder with a wide size distribution (0-63 μm) and artificially created pores has been sintered at the European Synchrotron Research Facilities up to 1050°C. X ray microtomography provided 3D images of the microstructure at successive times of the sintering cycle with a resolution of 1.6 μm. The evolution of microstrucural parameters, such as interparticle neck size and indentation, particle displacement, throughout sintering have been obtained by quantitative analysis of these images. The initial packing observed by microtomography has been discretized in order to generate a numerical packing made of approximately 20 000 spherical particles, which has been passed to a discrete element code that is able to predict new contacts, contact growth and the rate of approach for each of the initial particles. Densification and microstructure changes predicted by the simulation are then compared with 3D images. Particular attention is paid to the extent of particle rearrangement in the packing.