The common scale-up methodology for gas–solid spouted bed that has been reported in the literature is based on matching dimensionless groups. This methodology has been validated by measuring global hydrodynamic parameters and non-validated by limited point measurements of solids holdup and velocity. Therefore, the purpose of this work is to implement our advanced non-invasive gamma-ray computed tomography (CT) technique to assess and to demonstrate that the reported set of the dimensionless groups are not adequate in capturing all the interplay phenomena for achieving similarity in local solids and gas holdups cross-sectional distributions and their radial profiles along the bed height measured in 0.076 and 0.152 m spouted beds. The results clearly identified the three regions (spout, annulus and fountain) of gas–solid spouted beds and their solids structure. In addition, the reported results are valuable as a benchmarking data for CFD and DEM simulations.