This paper describes a novel approach for synthesis of scandium oxide (Sc₂O₃) microspheres based on sol–gel technique of internal gelation followed by neutron activation in a nuclear reactor to produce ⁴⁶Sc for use as radiotracers in radioactive particle tracking (RPT) experiments. The synthesis of scandium oxide microspheres of regular and spherical shapes essentially consists of formation of concentrated colloidal sol of the Sc(OH)₃ and transformation of this sol into a semi rigid gel followed by heating. The synthesized microspheres were characterized by X-ray diffraction, scanning electron microscopy, thermogravimetry analysis/differential thermal analysis, and surface area analyses. The neutron-activated microspheres were successfully used in RPT experiments to investigate hydrodynamics of solids in a pilot-scale liquid–solid fluidized bed.