Researchers have tested the potential of various polymer composites for use in radiation shielding. They are light and non-toxic compared to Pb and have potential as shielding in diagnostic radiology where low-energy photons are predominantly used. This study documents the production of four composites using the combination of a base, i.e. high-density polyethylene (HDPE) polymer, and four other elements/compounds, i.e. molybdenum, molybdenum carbide, tungsten, or tungsten carbide. The resulting composites were synthesized in the form of 20 disks, each with a thickness of 2 mm. The disks were irradiated by a kilovoltage X-ray source (1.5 cm2 field size). The mass attenuation coefficient (?m), half value layer (HVL), mean free path (MFP), and equivalent atomic number of the disks were measured. We found that supplementing HDPE with additives enhanced the attenuation of beams; the ?m values of the composites were higher than that of the pure HDPE polymer. The ?m values of the measurement and calculation results were in good agreement with each other, with an average error of 5.2%. Among the three additive concentrations that were tested, i.e., 5, 10, and 15%, the 15% concentration in HDPE yielded the best shielding efficiency. Since they possess smaller values of HVL and MFP, the polymer composites containing W and WC performed the best at attenuating the radiation beams.