In order to discover the X-ray shielding ability of the composites, the results were compared to commercial lead (Pb) sheets (model RAS20 Calibrated Absorber Set) of four different thicknesses (i.e., 0.81, 1.63, 3.18 and 6.35 mm) (see Fig. 7) using a radiography unit of tube voltages 40–100 kV. The results show that although the lead sheets gave the lowest X-ray transmissions at each tube voltage when compared to all compositions of WO3-epoxy composites, the latter with 10 vol% of either micro-sized or nano-sized WO3, can be a substitute for Pb in X-ray shielding by increasing the sample thickness to ≥ 7 mm. Hence, the usage of lead in X-ray shielding can be substituted by WO3 whereby W is lighter and less toxic compared to Pb.