We implemented for the first time our radioactive particle tracking as an advanced noninvasive technique to further evaluate and validate our newly developed mechanistic scale-up methodology based on matching the radial profile of the gas holdup. Two spouted beds with diameters of 0.076 and 0.152 m were used. Three sets of conditions were implemented; i.e., conditions of the reference case, conditions that provided a gas-holdup radial profile similar to that of the reference case, and conditions that provided a gas-holdup radial profile dissimilar to that of the reference case. The results confirm the validation of the scale-up methodology in terms of obtaining closer dimensionless values and radial profiles of components of the particle velocity, normal stress, shear stress, and turbulent kinetic energy. The results further advance the understanding of gas-solids spouted beds, provide deeper insight into the solids dynamics of the beds and present important benchmarking data for validating computational fluid dynamics codes and models.